[{"Name":"The Study of Life","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"The Nature of Biology","Duration":"7m 14s","ChapterTopicVideoID":23234,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.790","Text":"Hi, today we\u0027ll study the nature of biology."},{"Start":"00:02.790 ","End":"00:03.990","Text":"By the end of this section,"},{"Start":"00:03.990 ","End":"00:07.320","Text":"you\u0027ll be able to identify and describe the properties of life,"},{"Start":"00:07.320 ","End":"00:10.545","Text":"describe the levels of organization among living things,"},{"Start":"00:10.545 ","End":"00:13.740","Text":"recognize and interpret a phylogenetic tree,"},{"Start":"00:13.740 ","End":"00:16.755","Text":"and list examples of different sub-disciplines in biology."},{"Start":"00:16.755 ","End":"00:19.470","Text":"For biologists, life is a set of characteristics"},{"Start":"00:19.470 ","End":"00:22.620","Text":"that distinguish living things from non-living things."},{"Start":"00:22.620 ","End":"00:27.900","Text":"All living organisms share several key properties, such as order."},{"Start":"00:27.900 ","End":"00:32.495","Text":"Organisms are remarkably organized structures that are composed of 1 or more cells."},{"Start":"00:32.495 ","End":"00:34.895","Text":"Cells are made of molecules, made of atoms."},{"Start":"00:34.895 ","End":"00:37.880","Text":"Many cells build structures and we\u0027ll soon see that."},{"Start":"00:37.880 ","End":"00:40.565","Text":"Another property is the response to environment."},{"Start":"00:40.565 ","End":"00:42.860","Text":"Organisms respond to diverse stimuli."},{"Start":"00:42.860 ","End":"00:46.535","Text":"For example, bacteria can move towards or away from certain chemicals."},{"Start":"00:46.535 ","End":"00:49.360","Text":"Plants can bend or grow towards a source of light."},{"Start":"00:49.360 ","End":"00:51.735","Text":"Energy processing."},{"Start":"00:51.735 ","End":"00:55.895","Text":"All organisms use a source of energy for their metabolomic activities."},{"Start":"00:55.895 ","End":"01:00.470","Text":"Some organisms capture energy from the sun and convert it into chemical energy in food."},{"Start":"01:00.470 ","End":"01:04.040","Text":"Others use chemical energy in molecules they take in as food."},{"Start":"01:04.040 ","End":"01:08.975","Text":"Regulation, even small single-celled organisms are extremely complex."},{"Start":"01:08.975 ","End":"01:10.265","Text":"Inside each cell,"},{"Start":"01:10.265 ","End":"01:15.875","Text":"minuscule organelles perform functions and allow respiration, growth, and reproduction."},{"Start":"01:15.875 ","End":"01:19.715","Text":"All organisms need to regulate various parameters in order to maintain life."},{"Start":"01:19.715 ","End":"01:23.135","Text":"For example, water levels in the cell must stay at a certain range."},{"Start":"01:23.135 ","End":"01:24.890","Text":"Too much water can cause the cell walls to"},{"Start":"01:24.890 ","End":"01:27.485","Text":"tear and too little water could dry the cell up."},{"Start":"01:27.485 ","End":"01:30.754","Text":"Homeostasis literally means steady-state."},{"Start":"01:30.754 ","End":"01:34.430","Text":"In order to function, cells require appropriate conditions,"},{"Start":"01:34.430 ","End":"01:36.905","Text":"such as proper temperature, acidity,"},{"Start":"01:36.905 ","End":"01:39.875","Text":"and appropriate concentrations of diverse chemicals."},{"Start":"01:39.875 ","End":"01:42.980","Text":"These conditions may have a change from one moment to the next."},{"Start":"01:42.980 ","End":"01:47.345","Text":"Organisms are able to maintain internal conditions within a narrow range,"},{"Start":"01:47.345 ","End":"01:52.665","Text":"almost constantly, despite environmental changes through homeostasis."},{"Start":"01:52.665 ","End":"01:54.920","Text":"For example, an organism needs to regulate"},{"Start":"01:54.920 ","End":"01:57.980","Text":"body temperature through the thermoregulation process."},{"Start":"01:57.980 ","End":"02:01.475","Text":"Organisms that live in cold climates, such as the polar bear,"},{"Start":"02:01.475 ","End":"02:05.990","Text":"have body structures that help them withstand low temperatures and conserve body heat."},{"Start":"02:05.990 ","End":"02:09.170","Text":"Structures that aid in this type of insulation include fur,"},{"Start":"02:09.170 ","End":"02:11.120","Text":"feathers, blubber, and fat."},{"Start":"02:11.120 ","End":"02:12.920","Text":"On the other hand, in hot climates,"},{"Start":"02:12.920 ","End":"02:15.769","Text":"organisms have methods such as perspiration,"},{"Start":"02:15.769 ","End":"02:16.843","Text":"humans or anting in dogs,"},{"Start":"02:16.843 ","End":"02:19.145","Text":"that help them to shed excess body heat."},{"Start":"02:19.145 ","End":"02:20.810","Text":"Growth and development,"},{"Start":"02:20.810 ","End":"02:24.330","Text":"all organisms grow and develop during their lifetime."},{"Start":"02:24.330 ","End":"02:27.290","Text":"Reproduction, all organisms produce offspring"},{"Start":"02:27.290 ","End":"02:30.800","Text":"carrying their own genetic data encoded by strands of DNA."},{"Start":"02:30.800 ","End":"02:35.165","Text":"This data ensures that the offspring will carry trace similar to it\u0027s parents."},{"Start":"02:35.165 ","End":"02:40.300","Text":"Evolutionary adaptation, although offspring carry traits similar to their parents,"},{"Start":"02:40.300 ","End":"02:42.730","Text":"these traits differ to a certain extent."},{"Start":"02:42.730 ","End":"02:46.480","Text":"The cases where these differences give their carrier an advantage over others,"},{"Start":"02:46.480 ","End":"02:48.940","Text":"they\u0027ll be passed over to the next-generation."},{"Start":"02:48.940 ","End":"02:51.100","Text":"This allows organisms to adapt better to"},{"Start":"02:51.100 ","End":"02:54.205","Text":"their environment and to cope with environmental changes."},{"Start":"02:54.205 ","End":"02:59.185","Text":"We\u0027ll now take a short look at 2 of these properties, order and evolution."},{"Start":"02:59.185 ","End":"03:02.470","Text":"Living things are highly organized parts of a hierarchy."},{"Start":"03:02.470 ","End":"03:05.680","Text":"New properties emerge at each level in the biological hierarchy,"},{"Start":"03:05.680 ","End":"03:07.660","Text":"and with each step upwards from atoms,"},{"Start":"03:07.660 ","End":"03:12.265","Text":"new properties emerged as a result of interactions between the lower-level components."},{"Start":"03:12.265 ","End":"03:14.740","Text":"Atoms are the basic units of matter."},{"Start":"03:14.740 ","End":"03:17.860","Text":"When grouped together they form molecules."},{"Start":"03:17.860 ","End":"03:21.274","Text":"The molecules can be small, like water molecules,"},{"Start":"03:21.274 ","End":"03:24.400","Text":"H2O or carbon dioxide CO2,"},{"Start":"03:24.400 ","End":"03:28.295","Text":"they could be larger and more complex molecules like this one we see here."},{"Start":"03:28.295 ","End":"03:30.470","Text":"Then they\u0027re called macromolecules,"},{"Start":"03:30.470 ","End":"03:34.535","Text":"molecules group and they form organelles."},{"Start":"03:34.535 ","End":"03:39.275","Text":"These serve as tiny organs that perform complex actions in every living cell."},{"Start":"03:39.275 ","End":"03:42.769","Text":"Cells are the basic unit of structure and function of an organism."},{"Start":"03:42.769 ","End":"03:45.170","Text":"The cells are the lowest level of organization that"},{"Start":"03:45.170 ","End":"03:47.980","Text":"can perform all activities required for life."},{"Start":"03:47.980 ","End":"03:50.485","Text":"Multi-celled life forms such as their cells,"},{"Start":"03:50.485 ","End":"03:53.120","Text":"many cells can group into tissues,"},{"Start":"03:53.120 ","End":"03:55.430","Text":"like these muscular tissues of the stomach."},{"Start":"03:55.430 ","End":"03:58.565","Text":"In turn, several tissue layers can form organs,"},{"Start":"03:58.565 ","End":"04:00.280","Text":"and here we see a stomach."},{"Start":"04:00.280 ","End":"04:03.365","Text":"The stomach along with other organs such as the intestines,"},{"Start":"04:03.365 ","End":"04:05.410","Text":"form the digestive system,"},{"Start":"04:05.410 ","End":"04:08.210","Text":"a good example for organ systems."},{"Start":"04:08.210 ","End":"04:11.015","Text":"These systems combined give us a whole organism."},{"Start":"04:11.015 ","End":"04:14.210","Text":"Organisms are grouped into populations."},{"Start":"04:14.210 ","End":"04:19.475","Text":"All plant and animal populations in a given area comprise a community."},{"Start":"04:19.475 ","End":"04:23.720","Text":"Ecosystems include the community and the environment in which they live."},{"Start":"04:23.720 ","End":"04:25.880","Text":"Organisms interact with their environment,"},{"Start":"04:25.880 ","End":"04:27.395","Text":"change in matter and energy."},{"Start":"04:27.395 ","End":"04:31.370","Text":"This environment includes both non-living factors and other organisms."},{"Start":"04:31.370 ","End":"04:36.125","Text":"Chemical nutrients are recycled within an ecosystem and energy flows through it."},{"Start":"04:36.125 ","End":"04:41.245","Text":"Generally, energy flows from sunlight to producers and consumers."},{"Start":"04:41.245 ","End":"04:46.490","Text":"The biosphere encompasses all the ecosystems on Earth."},{"Start":"04:46.490 ","End":"04:50.840","Text":"Charles Darwin, a 19th century British naturalist and the"},{"Start":"04:50.840 ","End":"04:55.325","Text":"father of the evolutionary theory, made several observations."},{"Start":"04:55.325 ","End":"05:01.130","Text":"He noticed that in each generation there are more offspring than adults."},{"Start":"05:01.130 ","End":"05:05.975","Text":"Nevertheless, the population size remains constant."},{"Start":"05:05.975 ","End":"05:09.710","Text":"He also noticed that resources are limited and therefore he"},{"Start":"05:09.710 ","End":"05:15.710","Text":"inferred the individuals within the population must compete for resources."},{"Start":"05:15.710 ","End":"05:19.360","Text":"He also noticed that individuals vary from one another,"},{"Start":"05:19.360 ","End":"05:21.830","Text":"and that then these variations are heritable."},{"Start":"05:21.830 ","End":"05:25.070","Text":"Therefore, he concluded that some individuals will inherit"},{"Start":"05:25.070 ","End":"05:29.645","Text":"traits that will give them an advantage for survival and reproduction over others."},{"Start":"05:29.645 ","End":"05:31.840","Text":"Through these 2 inferences,"},{"Start":"05:31.840 ","End":"05:34.959","Text":"he reached the theory of natural selection."},{"Start":"05:34.959 ","End":"05:39.740","Text":"Theory states that over time the population changes as"},{"Start":"05:39.740 ","End":"05:45.330","Text":"advantages characteristics become more common throughout the generations."},{"Start":"05:46.310 ","End":"05:49.700","Text":"A diagram called a phylogenetic tree can be used to"},{"Start":"05:49.700 ","End":"05:52.220","Text":"show evolutionary relationships among organisms."},{"Start":"05:52.220 ","End":"05:56.110","Text":"We can see that the origin of life gave rise to plants,"},{"Start":"05:56.110 ","End":"05:59.785","Text":"to fungi, to microorganisms, and to animals."},{"Start":"05:59.785 ","End":"06:02.710","Text":"Here we can see that animals are also very diverse."},{"Start":"06:02.710 ","End":"06:06.860","Text":"We have vertebrates, vertebrates themselves split up into different animal groups,"},{"Start":"06:06.860 ","End":"06:08.590","Text":"we have here fish, reptiles,"},{"Start":"06:08.590 ","End":"06:11.685","Text":"amphibians, birds, and mammals."},{"Start":"06:11.685 ","End":"06:14.955","Text":"As the world of living creatures are so diverse,"},{"Start":"06:14.955 ","End":"06:20.020","Text":"the fields of biology and the scientific investigation of life are also very diverse."},{"Start":"06:20.020 ","End":"06:21.820","Text":"Some examples include zoology,"},{"Start":"06:21.820 ","End":"06:24.190","Text":"which is the study of living animals."},{"Start":"06:24.190 ","End":"06:26.560","Text":"Botany, which is the study of plants."},{"Start":"06:26.560 ","End":"06:30.895","Text":"Microbiology is the study of microorganisms such as bacteria."},{"Start":"06:30.895 ","End":"06:34.480","Text":"We also have different fields of what we want to study."},{"Start":"06:34.480 ","End":"06:39.935","Text":"Anatomy is the study of the inner structure of the body."},{"Start":"06:39.935 ","End":"06:44.330","Text":"Cell biology focuses on the inner structures of the cell itself."},{"Start":"06:44.330 ","End":"06:49.970","Text":"Molecular biology is the study of the molecules usually inferring to DNA."},{"Start":"06:49.970 ","End":"06:54.605","Text":"Neurobiology is the study of the brain and the nervous system."},{"Start":"06:54.605 ","End":"06:56.940","Text":"These are of course just some examples,"},{"Start":"06:56.940 ","End":"06:58.610","Text":"many of these fields overlap each other."},{"Start":"06:58.610 ","End":"07:04.475","Text":"For example, a researcher working on a symbiosis between bacteria and plants might use"},{"Start":"07:04.475 ","End":"07:07.550","Text":"molecular techniques to better understand"},{"Start":"07:07.550 ","End":"07:13.800","Text":"the cellular processes of both plants and bacteria."}],"ID":24092},{"Watched":false,"Name":"The Scientific Method","Duration":"5m 21s","ChapterTopicVideoID":23235,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.880","Text":"Hi. Today we\u0027re going to begin to introduce Biology."},{"Start":"00:02.880 ","End":"00:03.990","Text":"This section is titled,"},{"Start":"00:03.990 ","End":"00:05.250","Text":"the study of life."},{"Start":"00:05.250 ","End":"00:07.920","Text":"By the end of it, you\u0027ll be able to identify"},{"Start":"00:07.920 ","End":"00:10.665","Text":"the shared characteristics of the natural sciences,"},{"Start":"00:10.665 ","End":"00:14.190","Text":"describe the goals of basic science and applied science,"},{"Start":"00:14.190 ","End":"00:16.800","Text":"summarize the steps of the scientific method"},{"Start":"00:16.800 ","End":"00:20.565","Text":"and compare inductive reasoning with deductive reasoning."},{"Start":"00:20.565 ","End":"00:23.505","Text":"What does biology actually mean?"},{"Start":"00:23.505 ","End":"00:25.410","Text":"It\u0027s made of 2 Greek words,"},{"Start":"00:25.410 ","End":"00:28.320","Text":"Bios meaning life and logia meaning studies,"},{"Start":"00:28.320 ","End":"00:31.935","Text":"so biology means life studies, and will define it,"},{"Start":"00:31.935 ","End":"00:35.685","Text":"as the scientific investigation of living organisms,"},{"Start":"00:35.685 ","End":"00:39.375","Text":"their interactions with one another and with the environment,"},{"Start":"00:39.375 ","End":"00:41.715","Text":"but what is science?"},{"Start":"00:41.715 ","End":"00:45.560","Text":"This comes from the Latin word Scientia, meaning knowledge."},{"Start":"00:45.560 ","End":"00:50.030","Text":"Science is a human ongoing activity which attempts to describe,"},{"Start":"00:50.030 ","End":"00:52.550","Text":"investigate and understand the world and"},{"Start":"00:52.550 ","End":"00:57.035","Text":"the universe by rational means in mutually acceptable terms."},{"Start":"00:57.035 ","End":"00:58.740","Text":"Science has many fields,"},{"Start":"00:58.740 ","End":"01:01.280","Text":"the ones which are related to the physical world and it\u0027s"},{"Start":"01:01.280 ","End":"01:04.235","Text":"phenomenon are termed natural sciences."},{"Start":"01:04.235 ","End":"01:07.430","Text":"The natural sciences are concerned with the description,"},{"Start":"01:07.430 ","End":"01:11.015","Text":"prediction, and understanding of natural phenomena."},{"Start":"01:11.015 ","End":"01:16.355","Text":"Natural sciences can be divided into basic science and applied science."},{"Start":"01:16.355 ","End":"01:19.160","Text":"Basic science is aimed at expanding knowledge,"},{"Start":"01:19.160 ","End":"01:22.780","Text":"through scientific research to improve scientific theories."},{"Start":"01:22.780 ","End":"01:27.785","Text":"The basic science is aimed at understanding the prediction of natural phenomena,"},{"Start":"01:27.785 ","End":"01:32.585","Text":"and it has no expectation of short-term practical application of that knowledge."},{"Start":"01:32.585 ","End":"01:36.500","Text":"On the other hand, applied sciences are aimed at"},{"Start":"01:36.500 ","End":"01:40.820","Text":"solving practical problems using scientific knowledge and theories."},{"Start":"01:40.820 ","End":"01:44.270","Text":"Applied sciences strive to develop technology and"},{"Start":"01:44.270 ","End":"01:48.145","Text":"techniques to intervene and alter natural or other phenomena."},{"Start":"01:48.145 ","End":"01:51.170","Text":"A scientist is a person engaging in"},{"Start":"01:51.170 ","End":"01:56.045","Text":"systematic activity to acquire knowledge that describe and predicts the natural world."},{"Start":"01:56.045 ","End":"01:59.435","Text":"The scientific approach is based on a number of assumptions."},{"Start":"01:59.435 ","End":"02:04.880","Text":"First, all events are within the scope of human comprehension."},{"Start":"02:04.880 ","End":"02:10.250","Text":"Experiences must be explained with consistent terms."},{"Start":"02:10.250 ","End":"02:14.270","Text":"Generalization, which is the summary explanation of the observation,"},{"Start":"02:14.270 ","End":"02:17.465","Text":"must be testable, and last,"},{"Start":"02:17.465 ","End":"02:21.575","Text":"observations must be understandable and repeatable."},{"Start":"02:21.575 ","End":"02:27.095","Text":"The scientific method systematically describes and predicts phenomena in nature."},{"Start":"02:27.095 ","End":"02:31.475","Text":"This is a staged process following fixed steps,"},{"Start":"02:31.475 ","End":"02:34.430","Text":"the first of them being observation."},{"Start":"02:34.430 ","End":"02:37.550","Text":"Observation could be qualitative observations such as"},{"Start":"02:37.550 ","End":"02:41.015","Text":"the simple description of an object or phenomenon,"},{"Start":"02:41.015 ","End":"02:43.625","Text":"say daisies have petals,"},{"Start":"02:43.625 ","End":"02:46.265","Text":"or of quantitative observations,"},{"Start":"02:46.265 ","End":"02:47.735","Text":"which is the systematic,"},{"Start":"02:47.735 ","End":"02:50.000","Text":"careful measurement through statistical,"},{"Start":"02:50.000 ","End":"02:52.670","Text":"mathematical or computational techniques,"},{"Start":"02:52.670 ","End":"02:56.300","Text":"say counting the petals in 100 daisies."},{"Start":"02:56.300 ","End":"03:00.110","Text":"The next step is defining a problem that we want to study."},{"Start":"03:00.110 ","End":"03:03.110","Text":"The next step is hypothesizing."},{"Start":"03:03.110 ","End":"03:06.815","Text":"An hypothesis is an initial untested generalization,"},{"Start":"03:06.815 ","End":"03:09.950","Text":"a proposed explanation for a phenomenon."},{"Start":"03:09.950 ","End":"03:13.915","Text":"Then we must test this hypothesis using controls."},{"Start":"03:13.915 ","End":"03:15.405","Text":"Using the controls,"},{"Start":"03:15.405 ","End":"03:19.115","Text":"allows us to confirm that the experimental results are valid."},{"Start":"03:19.115 ","End":"03:23.465","Text":"The control group and the experimental group differ in only one factor,"},{"Start":"03:23.465 ","End":"03:26.200","Text":"known as the controlled variable."},{"Start":"03:26.200 ","End":"03:30.290","Text":"The results of a test allow us to draw conclusions and"},{"Start":"03:30.290 ","End":"03:34.255","Text":"conclusions of many tests allow us to build a theory."},{"Start":"03:34.255 ","End":"03:37.700","Text":"This is a general scientifically acceptable principle,"},{"Start":"03:37.700 ","End":"03:41.690","Text":"suggesting an explanation for the observed facts."},{"Start":"03:41.690 ","End":"03:43.760","Text":"After we build a theory,"},{"Start":"03:43.760 ","End":"03:47.350","Text":"we may test this theory over and over to validate it."},{"Start":"03:47.350 ","End":"03:49.950","Text":"Drawing conclusions in building a theory,"},{"Start":"03:49.950 ","End":"03:55.415","Text":"we find 2 types of logical reasoning: Inductive reasoning and deductive reasoning."},{"Start":"03:55.415 ","End":"04:00.985","Text":"Inductive reasoning is when related observations lead us to a general conclusion."},{"Start":"04:00.985 ","End":"04:04.205","Text":"Here we first collect specific data,"},{"Start":"04:04.205 ","End":"04:06.920","Text":"we analyze it and look for patterns,"},{"Start":"04:06.920 ","End":"04:09.155","Text":"and then we can form a general theory."},{"Start":"04:09.155 ","End":"04:14.225","Text":"Of course, this theory may be tested and other specific examples."},{"Start":"04:14.225 ","End":"04:16.910","Text":"For example, in brain studies, in such studies,"},{"Start":"04:16.910 ","End":"04:19.850","Text":"many live brains are observed while doing a specific activity,"},{"Start":"04:19.850 ","End":"04:22.120","Text":"such as viewing a specific object,"},{"Start":"04:22.120 ","End":"04:23.810","Text":"in this example, a cat."},{"Start":"04:23.810 ","End":"04:27.140","Text":"The part of the brain that lights up in the course of this activity,"},{"Start":"04:27.140 ","End":"04:32.225","Text":"is then predicted to be the part controlling the response of the selected stimulus."},{"Start":"04:32.225 ","End":"04:34.730","Text":"In this case, in order to test this theory,"},{"Start":"04:34.730 ","End":"04:38.960","Text":"scientists can stimulate different brain and check for the reaction."},{"Start":"04:38.960 ","End":"04:42.430","Text":"Does this man actually suddenly see cats?"},{"Start":"04:42.430 ","End":"04:45.525","Text":"On the other hand, in deductive reasoning,"},{"Start":"04:45.525 ","End":"04:49.520","Text":"a general law is used to forecast specific results."},{"Start":"04:49.520 ","End":"04:53.445","Text":"Here, a general hypothesis is made the first,"},{"Start":"04:53.445 ","End":"04:55.740","Text":"then the data is analyzed,"},{"Start":"04:55.740 ","End":"05:01.445","Text":"and we can form a specific theory about what might happen because of this general rule."},{"Start":"05:01.445 ","End":"05:08.165","Text":"For example, we might predict that if the climate becomes warmer in a particular region,"},{"Start":"05:08.165 ","End":"05:11.030","Text":"the distribution of plants and animals might change."},{"Start":"05:11.030 ","End":"05:15.290","Text":"We can then check this prediction by testing, for example,"},{"Start":"05:15.290 ","End":"05:21.570","Text":"modification of agricultural areas into deserts or extinction of plants and animals."}],"ID":24093},{"Watched":false,"Name":"Exercise 1","Duration":"2m 9s","ChapterTopicVideoID":23236,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.010 ","End":"00:04.725","Text":"This question is about the scientific method."},{"Start":"00:04.725 ","End":"00:07.560","Text":"The first part of the question we\u0027re asked to order"},{"Start":"00:07.560 ","End":"00:11.940","Text":"the scientific method steps with the process of solving the problem."},{"Start":"00:11.940 ","End":"00:15.495","Text":"The scientific method steps are given here by numbers."},{"Start":"00:15.495 ","End":"00:20.410","Text":"The process of solving the problem as given here in these rectangles."},{"Start":"00:20.860 ","End":"00:24.095","Text":"The first one, is their observation?"},{"Start":"00:24.095 ","End":"00:25.970","Text":"It\u0027s a problematic observations,"},{"Start":"00:25.970 ","End":"00:27.920","Text":"so we\u0027re not talking about my TV works,"},{"Start":"00:27.920 ","End":"00:31.520","Text":"we\u0027re talking about my radio doesn\u0027t play music."},{"Start":"00:31.520 ","End":"00:34.925","Text":"The observation causes us to ask a question."},{"Start":"00:34.925 ","End":"00:38.180","Text":"The question is, why doesn\u0027t my radio work?"},{"Start":"00:38.180 ","End":"00:44.135","Text":"The hypothesis as an answer that we give may answer the question about the observation."},{"Start":"00:44.135 ","End":"00:47.525","Text":"Though it\u0027s not proved, it\u0027s just an idea that we might have."},{"Start":"00:47.525 ","End":"00:54.035","Text":"In this case, the idea is that maybe the electrical outlet is dysfunctional."},{"Start":"00:54.035 ","End":"00:56.240","Text":"This hypothesis gives rise to"},{"Start":"00:56.240 ","End":"00:59.675","Text":"a prediction because if something is actually wrong with my outlet,"},{"Start":"00:59.675 ","End":"01:01.625","Text":"so anything else I plug in,"},{"Start":"01:01.625 ","End":"01:05.600","Text":"such as the TV also won\u0027t work when I plug it into the same outlet."},{"Start":"01:05.600 ","End":"01:09.170","Text":"This gives us the option to experiment."},{"Start":"01:09.170 ","End":"01:12.770","Text":"We can plug the TV into the outlet and check the outcome."},{"Start":"01:12.770 ","End":"01:16.470","Text":"In this case, the result is that my TV works."},{"Start":"01:17.140 ","End":"01:20.060","Text":"Part 2 of the question asks us,"},{"Start":"01:20.060 ","End":"01:22.220","Text":"if based on the results of the experiment,"},{"Start":"01:22.220 ","End":"01:24.470","Text":"the hypothesis is indeed correct."},{"Start":"01:24.470 ","End":"01:27.890","Text":"Our hypothesis was that the electrical outlet is dysfunctional."},{"Start":"01:27.890 ","End":"01:31.175","Text":"We checked it by plugging the TV into the same outlet,"},{"Start":"01:31.175 ","End":"01:33.170","Text":"and the result was that the TV works."},{"Start":"01:33.170 ","End":"01:35.390","Text":"The result actually shows that"},{"Start":"01:35.390 ","End":"01:37.940","Text":"the prediction that if something is wrong"},{"Start":"01:37.940 ","End":"01:40.565","Text":"with the outlet the TV also won\u0027t work, is wrong."},{"Start":"01:40.565 ","End":"01:43.915","Text":"Therefore, we can cross out this hypothesis."},{"Start":"01:43.915 ","End":"01:47.330","Text":"Part 3 of the question asks us if indeed"},{"Start":"01:47.330 ","End":"01:52.320","Text":"the hypothesis is incorrect and propose some alternative hypotheses."},{"Start":"01:52.460 ","End":"01:54.560","Text":"If the radio doesn\u0027t work,"},{"Start":"01:54.560 ","End":"01:56.180","Text":"I know the problem is not the outlet,"},{"Start":"01:56.180 ","End":"01:58.700","Text":"so maybe the radio is just not turned on."},{"Start":"01:58.700 ","End":"02:00.755","Text":"Let\u0027s try to turn it on and see."},{"Start":"02:00.755 ","End":"02:03.995","Text":"If indeed the radio is turned on and still it doesn\u0027t work,"},{"Start":"02:03.995 ","End":"02:06.535","Text":"maybe the radio itself has broken."},{"Start":"02:06.535 ","End":"02:09.340","Text":"We\u0027ve answered this question."}],"ID":24094},{"Watched":false,"Name":"Exercise 2","Duration":"1m 33s","ChapterTopicVideoID":23237,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.200 ","End":"00:03.765","Text":"This is a question about scientific reasoning."},{"Start":"00:03.765 ","End":"00:06.780","Text":"Here we need to decide if each of the following statements"},{"Start":"00:06.780 ","End":"00:10.185","Text":"is an example of inductive or of deductive reasoning."},{"Start":"00:10.185 ","End":"00:11.610","Text":"A short reminder,"},{"Start":"00:11.610 ","End":"00:16.560","Text":"inductive reasoning is when related observations lead us to a conclusion."},{"Start":"00:16.560 ","End":"00:22.349","Text":"While deductive reasoning is when we use a general law to forecast specific results."},{"Start":"00:22.349 ","End":"00:24.315","Text":"Let\u0027s take a look at the first one."},{"Start":"00:24.315 ","End":"00:28.155","Text":"The teacher used PowerPoint in the last few classes,"},{"Start":"00:28.155 ","End":"00:31.305","Text":"therefore, the teacher will use PowerPoint tomorrow."},{"Start":"00:31.305 ","End":"00:36.169","Text":"Here what we\u0027re doing is using related observations to lead to a conclusion."},{"Start":"00:36.169 ","End":"00:41.015","Text":"The related observations are the teacher using PowerPoint in the last few classes."},{"Start":"00:41.015 ","End":"00:46.265","Text":"The conclusion is that therefore the teacher will use PowerPoint again tomorrow."},{"Start":"00:46.265 ","End":"00:51.255","Text":"This is a case of inductive reasoning. Example b."},{"Start":"00:51.255 ","End":"00:53.370","Text":"All chimpanzees are mammals,"},{"Start":"00:53.370 ","End":"00:55.320","Text":"all mammals have kidneys,"},{"Start":"00:55.320 ","End":"00:57.965","Text":"therefore, all chimpanzees have kidneys."},{"Start":"00:57.965 ","End":"01:00.170","Text":"Here what we\u0027re using is a general law."},{"Start":"01:00.170 ","End":"01:03.500","Text":"The general law is that chimpanzees are mammals and the mammals have kidneys."},{"Start":"01:03.500 ","End":"01:07.970","Text":"We\u0027re using this general law to forecast specific results,"},{"Start":"01:07.970 ","End":"01:10.230","Text":"i.e., chimpanzees have kidneys,"},{"Start":"01:10.230 ","End":"01:13.950","Text":"and therefore we\u0027re talking about deductive reasoning."},{"Start":"01:14.230 ","End":"01:18.485","Text":"Example c. Gravity makes things fall."},{"Start":"01:18.485 ","End":"01:22.190","Text":"My wallet fell from the table due to gravity."},{"Start":"01:22.190 ","End":"01:27.515","Text":"Again, here we\u0027re making a forecast about specific results from a general law,"},{"Start":"01:27.515 ","End":"01:29.345","Text":"which is that gravity makes things fall."},{"Start":"01:29.345 ","End":"01:33.300","Text":"Therefore, again, we\u0027re talking about deductive reasoning."}],"ID":24095},{"Watched":false,"Name":"Exercise 3","Duration":"1m 34s","ChapterTopicVideoID":23238,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.715","Text":"This is a question about scientific reasoning."},{"Start":"00:02.715 ","End":"00:05.760","Text":"Here we need to decide if each of the following statements"},{"Start":"00:05.760 ","End":"00:09.315","Text":"is an example of inductive reasoning or of deductive reasoning."},{"Start":"00:09.315 ","End":"00:12.300","Text":"A quick reminder, inductive reasoning is when"},{"Start":"00:12.300 ","End":"00:15.540","Text":"related observations lead us to a conclusion,"},{"Start":"00:15.540 ","End":"00:22.010","Text":"while deductive reasoning is when a general law is used to forecast specific results."},{"Start":"00:22.010 ","End":"00:24.325","Text":"Let\u0027s take a look at example A,"},{"Start":"00:24.325 ","End":"00:27.490","Text":"my father was loud when he was angry."},{"Start":"00:27.490 ","End":"00:30.125","Text":"All fathers or loud when they\u0027re angry."},{"Start":"00:30.125 ","End":"00:33.545","Text":"What we\u0027re doing here is actually using related observations,"},{"Start":"00:33.545 ","End":"00:38.195","Text":"my father was loud when he was angry to reach a general conclusion."},{"Start":"00:38.195 ","End":"00:43.915","Text":"All fathers are loud when they are angry and this is the fact is inductive reasoning."},{"Start":"00:43.915 ","End":"00:48.915","Text":"B, my kindergarten teacher liked apples,"},{"Start":"00:48.915 ","End":"00:51.480","Text":"my 1st grade teacher liked apples,"},{"Start":"00:51.480 ","End":"00:54.370","Text":"my 2nd grade teacher will like apples too."},{"Start":"00:54.370 ","End":"00:57.380","Text":"What we\u0027re doing here is actually looking at related observations"},{"Start":"00:57.380 ","End":"01:01.670","Text":"about 2 teachers who liked apples in order to reach a conclusion,"},{"Start":"01:01.670 ","End":"01:04.370","Text":"which is that the third teacher will also like"},{"Start":"01:04.370 ","End":"01:08.200","Text":"apples and this in fact is inductive reasoning."},{"Start":"01:08.200 ","End":"01:15.140","Text":"Statements C, since all women are mortal and Madonna is a woman, Madonna is mortal."},{"Start":"01:15.140 ","End":"01:17.080","Text":"So we\u0027re looking here at a general law,"},{"Start":"01:17.080 ","End":"01:22.640","Text":"the general given law is that all women are mortal and"},{"Start":"01:22.640 ","End":"01:25.220","Text":"Madonna is a woman and that leads us to"},{"Start":"01:25.220 ","End":"01:29.045","Text":"forecast a specific result that Madonna is mortal."},{"Start":"01:29.045 ","End":"01:34.950","Text":"This is deductive reasoning where we use a general law to forecast specific results."}],"ID":24096},{"Watched":false,"Name":"Exercise 4","Duration":"1m 41s","ChapterTopicVideoID":23239,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.260 ","End":"00:06.450","Text":"This is a question about life itself and as biology is the study of life sciences,"},{"Start":"00:06.450 ","End":"00:08.340","Text":"we should be able to answer this."},{"Start":"00:08.340 ","End":"00:11.145","Text":"Part 1, is a car alive?"},{"Start":"00:11.145 ","End":"00:14.385","Text":"A quick reminder of the properties of life."},{"Start":"00:14.385 ","End":"00:16.545","Text":"The properties of life."},{"Start":"00:16.545 ","End":"00:18.585","Text":"First thing, order."},{"Start":"00:18.585 ","End":"00:22.875","Text":"Second, response to stimuli or environment."},{"Start":"00:22.875 ","End":"00:28.670","Text":"3, energy processing, regulation, homeostasis,"},{"Start":"00:28.670 ","End":"00:32.270","Text":"growth and development, reproduction,"},{"Start":"00:32.270 ","End":"00:35.870","Text":"last but not least, evolutionary adaptation."},{"Start":"00:35.870 ","End":"00:37.490","Text":"What does the car have?"},{"Start":"00:37.490 ","End":"00:39.850","Text":"Let\u0027s just take a look here."},{"Start":"00:39.850 ","End":"00:44.165","Text":"Well order, certainly car is built with a lot of order."},{"Start":"00:44.165 ","End":"00:46.590","Text":"Modern cars really respond to stimuli,"},{"Start":"00:46.590 ","End":"00:49.655","Text":"or even old cars, if you press on the pedals, I guess."},{"Start":"00:49.655 ","End":"00:51.428","Text":"Energy processing, sure,"},{"Start":"00:51.428 ","End":"00:52.535","Text":"the motor works pretty well."},{"Start":"00:52.535 ","End":"00:55.055","Text":"Regulation, the temperature should be regulated."},{"Start":"00:55.055 ","End":"00:58.280","Text":"Homeostasis, no. Growth and development."},{"Start":"00:58.280 ","End":"01:01.459","Text":"I hope your car does not grow, does not reproduce,"},{"Start":"01:01.459 ","End":"01:07.310","Text":"and cars do not go through evolutionary adaptation. Is a car alive?"},{"Start":"01:07.310 ","End":"01:10.050","Text":"The answer is no."},{"Start":"01:10.180 ","End":"01:15.095","Text":"Part 2, which are the key properties shared by all living organisms does it have?"},{"Start":"01:15.095 ","End":"01:19.010","Text":"Well, we\u0027ve said the first 4."},{"Start":"01:19.010 ","End":"01:21.710","Text":"Part 3, which properties does it lack?"},{"Start":"01:21.710 ","End":"01:22.940","Text":"We said the latter 4."},{"Start":"01:22.940 ","End":"01:25.085","Text":"Here we\u0027ve got them nicely colored."},{"Start":"01:25.085 ","End":"01:27.365","Text":"A car has order,"},{"Start":"01:27.365 ","End":"01:29.540","Text":"response to stimuli,"},{"Start":"01:29.540 ","End":"01:34.085","Text":"processes energy, and it has a certain amount of regulation in it."},{"Start":"01:34.085 ","End":"01:36.260","Text":"But the car lacks homeostasis,"},{"Start":"01:36.260 ","End":"01:41.370","Text":"growth and development, reproduction, and evolutionary adaptation."}],"ID":24097},{"Watched":false,"Name":"Exercise 5","Duration":"50s","ChapterTopicVideoID":23240,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.365","Text":"All right, which of these statements is false?"},{"Start":"00:04.365 ","End":"00:08.685","Text":"A, atoms exist within molecules or macromolecules,"},{"Start":"00:08.685 ","End":"00:11.355","Text":"which exist within organelles."},{"Start":"00:11.355 ","End":"00:15.045","Text":"Yeah, that\u0027s true atoms do exist in molecules and"},{"Start":"00:15.045 ","End":"00:19.590","Text":"molecules form organelles, so this is correct."},{"Start":"00:19.590 ","End":"00:23.040","Text":"B, ecosystems exist within communities."},{"Start":"00:23.040 ","End":"00:27.975","Text":"No, we already know that communities exist within ecosystems, not the opposite."},{"Start":"00:27.975 ","End":"00:33.180","Text":"We can already mark B as the wrong answer, the false one."},{"Start":"00:33.180 ","End":"00:34.785","Text":"Let\u0027s just check the others."},{"Start":"00:34.785 ","End":"00:37.350","Text":"C, cells exist within tissues,"},{"Start":"00:37.350 ","End":"00:41.425","Text":"yes, which exists within organs. Yes, they do."},{"Start":"00:41.425 ","End":"00:47.285","Text":"The organisms exist within populations which exist in communities, which is also true."},{"Start":"00:47.285 ","End":"00:51.330","Text":"Therefore, we can mark B as a false statement."}],"ID":24098},{"Watched":false,"Name":"Exercise 6","Duration":"1m 13s","ChapterTopicVideoID":23241,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.220 ","End":"00:06.570","Text":"Let\u0027s see. All populations taken together make up a,"},{"Start":"00:06.570 ","End":"00:10.065","Text":"an organism, a biosphere,"},{"Start":"00:10.065 ","End":"00:13.590","Text":"a community, or an ecosystem?"},{"Start":"00:13.590 ","End":"00:16.425","Text":"Let\u0027s have a little reminder here."},{"Start":"00:16.425 ","End":"00:26.230","Text":"Well, organisms form populations."},{"Start":"00:28.040 ","End":"00:32.170","Text":"Populations form communities."},{"Start":"00:33.460 ","End":"00:36.575","Text":"Communities form"},{"Start":"00:36.575 ","End":"00:44.620","Text":"ecosystems and"},{"Start":"00:44.620 ","End":"00:51.860","Text":"ecosystems taken together give us the one and only biosphere."},{"Start":"00:51.860 ","End":"00:54.995","Text":"Let\u0027s see. We\u0027re asked what populations,"},{"Start":"00:54.995 ","End":"00:59.105","Text":"form populations together make a community."},{"Start":"00:59.105 ","End":"01:03.140","Text":"Therefore, we can X out organism, biosphere."},{"Start":"01:03.140 ","End":"01:05.490","Text":"Mark community is the right answer,"},{"Start":"01:05.490 ","End":"01:10.140","Text":"except ecosystem and our answer is C, community."},{"Start":"01:10.140 ","End":"01:13.710","Text":"All populations together make up a community."}],"ID":24099},{"Watched":false,"Name":"Exercise 7","Duration":"1m 6s","ChapterTopicVideoID":23242,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.250","Text":"All members of 1 species living within a specific area form a biosphere,"},{"Start":"00:06.250 ","End":"00:12.000","Text":"ecosystem, population, community, or a country."},{"Start":"00:12.000 ","End":"00:14.310","Text":"Well, let\u0027s just make this a little bit easier by"},{"Start":"00:14.310 ","End":"00:18.300","Text":"saying all members of 1 species living in a specific area."},{"Start":"00:18.300 ","End":"00:20.760","Text":"Let\u0027s say zebras."},{"Start":"00:20.760 ","End":"00:22.920","Text":"We have here a lot of zebras."},{"Start":"00:22.920 ","End":"00:24.945","Text":"What do the zebras form together?"},{"Start":"00:24.945 ","End":"00:26.609","Text":"Do they form a biosphere?"},{"Start":"00:26.609 ","End":"00:29.420","Text":"Do they form an ecosystem or a population,"},{"Start":"00:29.420 ","End":"00:30.815","Text":"community, or country?"},{"Start":"00:30.815 ","End":"00:36.785","Text":"Well, the correct answer is that they form a population."},{"Start":"00:36.785 ","End":"00:41.075","Text":"Populations together may form communities."},{"Start":"00:41.075 ","End":"00:44.330","Text":"Many communities can form an ecosystem."},{"Start":"00:44.330 ","End":"00:49.595","Text":"Ecosystems together with all other things on Earth, form a biosphere."},{"Start":"00:49.595 ","End":"00:52.520","Text":"Countries, I\u0027m afraid from a different course."},{"Start":"00:52.520 ","End":"00:55.415","Text":"Therefore, we can mark A is wrong,"},{"Start":"00:55.415 ","End":"00:57.695","Text":"B is wrong, C is right,"},{"Start":"00:57.695 ","End":"00:59.195","Text":"D is wrong, E is wrong."},{"Start":"00:59.195 ","End":"01:00.455","Text":"Let\u0027s circle our answer,"},{"Start":"01:00.455 ","End":"01:06.780","Text":"C. All members of 1 species living within a specific area form a population."}],"ID":24100},{"Watched":false,"Name":"Exercise 8","Duration":"56s","ChapterTopicVideoID":23243,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.645","Text":"Here we\u0027re asked to find the right sequence of organization from smallest to largest."},{"Start":"00:06.645 ","End":"00:09.855","Text":"Let\u0027s start with A. Cell, organ."},{"Start":"00:09.855 ","End":"00:12.855","Text":"That sounds fine because organs are made of cells."},{"Start":"00:12.855 ","End":"00:19.440","Text":"Tissue. No. Cells form tissues which form organs,"},{"Start":"00:19.440 ","End":"00:21.630","Text":"which form organisms, so this one is wrong."},{"Start":"00:21.630 ","End":"00:23.205","Text":"All right, B."},{"Start":"00:23.205 ","End":"00:26.850","Text":"Cell, organ, organ system, that sounds fine."},{"Start":"00:26.850 ","End":"00:30.810","Text":"Tissue. Again, we\u0027ve got tissue at the wrong side of the sequence,"},{"Start":"00:30.810 ","End":"00:33.150","Text":"so cross this one out out."},{"Start":"00:33.150 ","End":"00:36.885","Text":"C, cell, tissue."},{"Start":"00:36.885 ","End":"00:39.480","Text":"That\u0027s already better. Organ, organism."},{"Start":"00:39.480 ","End":"00:45.725","Text":"Okay, that sounds great. Let\u0027s just look at D before we decide what our answer is."},{"Start":"00:45.725 ","End":"00:48.545","Text":"Organisms, organ system, no."},{"Start":"00:48.545 ","End":"00:51.440","Text":"Organ, tissue no, this all backwards."},{"Start":"00:51.440 ","End":"00:56.640","Text":"All right. I think we can easily mark C as our correct answer."}],"ID":24101},{"Watched":false,"Name":"Exercise 9","Duration":"1m 4s","ChapterTopicVideoID":23244,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.890 ","End":"00:04.740","Text":"All living things in a particular area together with"},{"Start":"00:04.740 ","End":"00:09.195","Text":"the non-living factors of that environment form a population,"},{"Start":"00:09.195 ","End":"00:13.110","Text":"ecosystem, community, or biosphere?"},{"Start":"00:13.110 ","End":"00:15.450","Text":"Well, let\u0027s take a look."},{"Start":"00:15.450 ","End":"00:19.515","Text":"Populations include all organisms of a certain species in an area,"},{"Start":"00:19.515 ","End":"00:22.845","Text":"and in this question here, we\u0027re talking about also non-living factors."},{"Start":"00:22.845 ","End":"00:26.595","Text":"A is wrong. Let\u0027s see ecosystem."},{"Start":"00:26.595 ","End":"00:31.130","Text":"An ecosystem includes all living things in a particular area,"},{"Start":"00:31.130 ","End":"00:34.060","Text":"together with the non-living factors of that environment."},{"Start":"00:34.060 ","End":"00:37.095","Text":"This works out, ecosystem is true."},{"Start":"00:37.095 ","End":"00:40.390","Text":"Let\u0027s look at the other answers before we decide what to circle."},{"Start":"00:40.390 ","End":"00:44.780","Text":"Community. Well, many populations form communities,"},{"Start":"00:44.780 ","End":"00:46.700","Text":"so this is wrong."},{"Start":"00:46.700 ","End":"00:48.845","Text":"A biosphere."},{"Start":"00:48.845 ","End":"00:52.040","Text":"Well, biosphere does include non-living factors"},{"Start":"00:52.040 ","End":"00:56.930","Text":"and living factors but altogether in all of Earth,"},{"Start":"00:56.930 ","End":"00:59.180","Text":"not in a particular area,"},{"Start":"00:59.180 ","End":"01:00.560","Text":"so biosphere is wrong,"},{"Start":"01:00.560 ","End":"01:04.980","Text":"and we can now decide that B is the correct answer."}],"ID":24102},{"Watched":false,"Name":"Exercise 10","Duration":"44s","ChapterTopicVideoID":23245,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.319","Text":"Which of the following sciences is not a natural science?"},{"Start":"00:04.319 ","End":"00:06.495","Text":"Well, a quick reminder,"},{"Start":"00:06.495 ","End":"00:10.170","Text":"natural sciences are related to the physical world and its phenomena."},{"Start":"00:10.170 ","End":"00:14.685","Text":"Since biology is the science of living things,"},{"Start":"00:14.685 ","End":"00:18.375","Text":"it is, in fact, a natural science."},{"Start":"00:18.375 ","End":"00:22.365","Text":"Space science, planets and stars,"},{"Start":"00:22.365 ","End":"00:25.500","Text":"those are, in fact, physical things."},{"Start":"00:25.500 ","End":"00:33.405","Text":"Chemistry is the science of chemicals which are natural, of course."},{"Start":"00:33.405 ","End":"00:39.300","Text":"But computer science is not related to the physical world and its phenomena,"},{"Start":"00:39.300 ","End":"00:42.284","Text":"and therefore, it is not a natural science,"},{"Start":"00:42.284 ","End":"00:45.220","Text":"and this is the answer that we will choose."}],"ID":24103},{"Watched":false,"Name":"Exercise 11","Duration":"1m 4s","ChapterTopicVideoID":23246,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.260 ","End":"00:05.520","Text":"Only a testable hypothesis is scientifically valid."},{"Start":"00:05.520 ","End":"00:08.527","Text":"What\u0027s the meaning of testable?"},{"Start":"00:08.527 ","End":"00:13.170","Text":"In this statement, testable hypothesis is valid."},{"Start":"00:13.170 ","End":"00:16.770","Text":"The scientific method states that the ideas that we bring,"},{"Start":"00:16.770 ","End":"00:20.670","Text":"the hypothesis must be testable."},{"Start":"00:20.670 ","End":"00:23.175","Text":"We must be able to test if they\u0027re right or wrong."},{"Start":"00:23.175 ","End":"00:26.625","Text":"If you can\u0027t show a hypothesis to be right or wrong,"},{"Start":"00:26.625 ","End":"00:28.935","Text":"it has no scientific validity."},{"Start":"00:28.935 ","End":"00:31.155","Text":"Let\u0027s take a look at the answers here."},{"Start":"00:31.155 ","End":"00:35.775","Text":"A, testable hypothesis means a controlled experiment"},{"Start":"00:35.775 ","End":"00:40.695","Text":"can indicate if the hypothesis is correct or incorrect, that is true."},{"Start":"00:40.695 ","End":"00:43.330","Text":"Let\u0027s have a look at the other answers before proceeding."},{"Start":"00:43.330 ","End":"00:46.055","Text":"There are several options in hypothesis,"},{"Start":"00:46.055 ","End":"00:48.259","Text":"one of which is correct."},{"Start":"00:48.259 ","End":"00:51.740","Text":"Well, that\u0027s not what testable hypothesis is talking about."},{"Start":"00:51.740 ","End":"00:54.485","Text":"C, the hypothesis has been proven wrong."},{"Start":"00:54.485 ","End":"00:59.060","Text":"Well, there\u0027s no way that that\u0027s scientifically valid. D, none of the above."},{"Start":"00:59.060 ","End":"01:00.995","Text":"Well, since we have our answer A,"},{"Start":"01:00.995 ","End":"01:04.650","Text":"we can circle this answer and give it."}],"ID":24104},{"Watched":false,"Name":"Exercise 12","Duration":"1m 22s","ChapterTopicVideoID":23247,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.865","Text":"The type of logical thinking that arrives to a general conclusion from"},{"Start":"00:03.865 ","End":"00:08.190","Text":"specific results or related observations is called, A,"},{"Start":"00:08.190 ","End":"00:10.500","Text":"deductive reasoning, B,"},{"Start":"00:10.500 ","End":"00:12.015","Text":"the scientific method,"},{"Start":"00:12.015 ","End":"00:16.590","Text":"C, hypothesis-based science or D, inductive reasoning."},{"Start":"00:16.590 ","End":"00:19.515","Text":"Let\u0027s start with A, deductive reasoning."},{"Start":"00:19.515 ","End":"00:25.394","Text":"Deductive reasoning is when we use a general law to forecasts specific results,"},{"Start":"00:25.394 ","End":"00:28.080","Text":"and here we do quite the opposite."},{"Start":"00:28.080 ","End":"00:31.680","Text":"Therefore, deductive reasoning is wrong."},{"Start":"00:31.680 ","End":"00:34.365","Text":"B, the scientific method."},{"Start":"00:34.365 ","End":"00:38.190","Text":"The scientific method consists of systematically describing or"},{"Start":"00:38.190 ","End":"00:42.410","Text":"predicting phenomena in nature by observing, asking,"},{"Start":"00:42.410 ","End":"00:45.470","Text":"hypothesizing, testing, reaching results,"},{"Start":"00:45.470 ","End":"00:49.565","Text":"and building a theory which is not the type of logical thinking we\u0027re talking about here,"},{"Start":"00:49.565 ","End":"00:52.390","Text":"and therefore scientific method is wrong."},{"Start":"00:52.390 ","End":"00:56.120","Text":"C, hypothesis-based science is"},{"Start":"00:56.120 ","End":"01:00.140","Text":"where science make an educated guess to explain a phenomenon in nature."},{"Start":"01:00.140 ","End":"01:04.640","Text":"Then they use observations to test their hypothesis which is again,"},{"Start":"01:04.640 ","End":"01:07.670","Text":"it\u0027s not the type of logical thinking that we\u0027re talking about."},{"Start":"01:07.670 ","End":"01:09.740","Text":"D, inductive reasoning."},{"Start":"01:09.740 ","End":"01:14.195","Text":"Inductive reasoning is the type of logical thinking that arrives to a general conclusion"},{"Start":"01:14.195 ","End":"01:19.430","Text":"using specific results or related observations and therefore,"},{"Start":"01:19.430 ","End":"01:21.690","Text":"D is the correct answer."}],"ID":24105},{"Watched":false,"Name":"Exercise 13","Duration":"1m 53s","ChapterTopicVideoID":23248,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.320 ","End":"00:04.500","Text":"A child notices that his rabbits that are regularly exposed to"},{"Start":"00:04.500 ","End":"00:09.120","Text":"the sun seem to grow more quickly than those not exposed to the sun."},{"Start":"00:09.120 ","End":"00:13.815","Text":"As a result, he determines that rabbits grow better when exposed to the sun."},{"Start":"00:13.815 ","End":"00:17.385","Text":"This example most closely resembles which type of reasoning?"},{"Start":"00:17.385 ","End":"00:21.420","Text":"Now since we are talking about inductive reasoning and deductive reasoning,"},{"Start":"00:21.420 ","End":"00:23.160","Text":"let\u0027s get just a quick reminder."},{"Start":"00:23.160 ","End":"00:25.425","Text":"In inductive reasoning,"},{"Start":"00:25.425 ","End":"00:34.300","Text":"we look at related observations."},{"Start":"00:36.890 ","End":"00:44.170","Text":"We use them to reach general conclusion."},{"Start":"00:46.660 ","End":"00:49.115","Text":"While in deductive reasoning,"},{"Start":"00:49.115 ","End":"00:53.810","Text":"we use general law"},{"Start":"00:53.810 ","End":"01:03.420","Text":"to forecast specific outcome."},{"Start":"01:05.120 ","End":"01:08.445","Text":"In this case, let\u0027s take a look we have here."},{"Start":"01:08.445 ","End":"01:10.290","Text":"The child is using"},{"Start":"01:10.290 ","End":"01:15.205","Text":"observations because the rabbits grow better or worse than in the sun,"},{"Start":"01:15.205 ","End":"01:18.695","Text":"and he uses those observations to"},{"Start":"01:18.695 ","End":"01:25.015","Text":"reach a general conclusion which rabbits grow better when exposed to sun."},{"Start":"01:25.015 ","End":"01:30.620","Text":"Therefore, inductive reasoning most closely resembles the examples seen here."},{"Start":"01:30.620 ","End":"01:32.585","Text":"Inductive reasoning would be true,"},{"Start":"01:32.585 ","End":"01:35.225","Text":"deductive reasoning does not work here."},{"Start":"01:35.225 ","End":"01:39.370","Text":"Answer is C, neither because null hypothesis was made."},{"Start":"01:39.370 ","End":"01:43.055","Text":"We already know that A works fine, so neither would not work."},{"Start":"01:43.055 ","End":"01:45.710","Text":"Both inductive and deductive reasoning,"},{"Start":"01:45.710 ","End":"01:47.990","Text":"no, because deductive reasoning is wrong."},{"Start":"01:47.990 ","End":"01:52.710","Text":"Therefore, we can choose our answer, inductive reasoning."}],"ID":24106},{"Watched":false,"Name":"Exercise 14","Duration":"53s","ChapterTopicVideoID":23232,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.410 ","End":"00:05.985","Text":"The smallest living biological structure unit is a tissue,"},{"Start":"00:05.985 ","End":"00:11.160","Text":"organelle, cell, or molecule. Well, let\u0027s have a look."},{"Start":"00:11.160 ","End":"00:14.939","Text":"Tissue is made out of many cells so cells are smaller."},{"Start":"00:14.939 ","End":"00:18.825","Text":"I think we can cross out tissue. B, organelle."},{"Start":"00:18.825 ","End":"00:21.900","Text":"Well, organelles are part of a living cell but"},{"Start":"00:21.900 ","End":"00:26.025","Text":"organelles are not standalone structures in nature."},{"Start":"00:26.025 ","End":"00:29.700","Text":"Therefore, they are not the smallest living biological structure."},{"Start":"00:29.700 ","End":"00:32.030","Text":"Cells, yeah."},{"Start":"00:32.030 ","End":"00:39.185","Text":"Most of life consists of unicellular creatures so cell would be correct,"},{"Start":"00:39.185 ","End":"00:40.910","Text":"and molecules are not alive."},{"Start":"00:40.910 ","End":"00:46.925","Text":"Again organelles are made of molecules and organelles together form a cell,"},{"Start":"00:46.925 ","End":"00:50.480","Text":"which is the smallest living biological structure."},{"Start":"00:50.480 ","End":"00:53.010","Text":"So our answer is cell."}],"ID":24090},{"Watched":false,"Name":"Exercise 15","Duration":"2m 9s","ChapterTopicVideoID":23233,"CourseChapterTopicPlaylistID":108179,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.710 ","End":"00:03.540","Text":"The organism present at the root of"},{"Start":"00:03.540 ","End":"00:08.505","Text":"a phylogenetic tree represents the organism that evolved most recently,"},{"Start":"00:08.505 ","End":"00:12.345","Text":"first from mammals, or most accurately?"},{"Start":"00:12.345 ","End":"00:17.970","Text":"Well, unlike regular family tree that we may know,"},{"Start":"00:17.970 ","End":"00:20.790","Text":"and we have say a grandmother and a grandfather,"},{"Start":"00:20.790 ","End":"00:24.000","Text":"other second set of them."},{"Start":"00:24.000 ","End":"00:31.060","Text":"We have our parents here and who had us."},{"Start":"00:31.790 ","End":"00:41.070","Text":"This is, let\u0027s say from past to present."},{"Start":"00:41.070 ","End":"00:44.510","Text":"A phylogenetic tree instead of looking at ourselves,"},{"Start":"00:44.510 ","End":"00:45.800","Text":"putting ourselves in the center,"},{"Start":"00:45.800 ","End":"00:48.680","Text":"the common ancestor, in the center."},{"Start":"00:48.680 ","End":"00:58.230","Text":"The common ancestor branches off to different species that evolved from him."},{"Start":"00:58.930 ","End":"01:02.420","Text":"Each of these species is actually the common ancestor"},{"Start":"01:02.420 ","End":"01:05.660","Text":"to other species that evolved in turn."},{"Start":"01:05.660 ","End":"01:08.780","Text":"So this one had 2 species,"},{"Start":"01:08.780 ","End":"01:12.389","Text":"and this one got extinct at a certain point in time and"},{"Start":"01:12.389 ","End":"01:16.955","Text":"this one evolve into 2 more species."},{"Start":"01:16.955 ","End":"01:19.880","Text":"While these just continue to go down until present."},{"Start":"01:19.880 ","End":"01:23.135","Text":"If you put a timescale here, we\u0027ll see the opposite."},{"Start":"01:23.135 ","End":"01:30.160","Text":"We go from the past to present."},{"Start":"01:30.900 ","End":"01:35.170","Text":"Let\u0027s look again at the root of a phylogenetic tree."},{"Start":"01:35.170 ","End":"01:38.938","Text":"We have the organism that evolved most recently, no."},{"Start":"01:38.938 ","End":"01:41.275","Text":"The recent ones are at the top."},{"Start":"01:41.275 ","End":"01:44.755","Text":"First that works out fine."},{"Start":"01:44.755 ","End":"01:50.718","Text":"Let\u0027s erase most recently, I\u0027ll choose first."},{"Start":"01:50.718 ","End":"01:53.984","Text":"From mammals, there\u0027s nothing to do with that at all, and most accurately,"},{"Start":"01:53.984 ","End":"01:58.885","Text":"is inaccurate answer for sure."},{"Start":"01:58.885 ","End":"02:01.465","Text":"Here we got our answer b,"},{"Start":"02:01.465 ","End":"02:04.450","Text":"the organism present at the root of a phylogenetic tree"},{"Start":"02:04.450 ","End":"02:08.120","Text":"represents the organism that evolved first."}],"ID":24091}],"Thumbnail":null,"ID":108179},{"Name":"The Chemical Foundation of Life","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"The Building Blocks of Matter","Duration":"9m 12s","ChapterTopicVideoID":31851,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":false,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[],"ID":34106},{"Watched":false,"Name":"Water The Basis of Life","Duration":"9m 45s","ChapterTopicVideoID":23254,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.470 ","End":"00:04.350","Text":"Hey, there. We\u0027re learning about the chemical foundation of life."},{"Start":"00:04.350 ","End":"00:06.645","Text":"Today we\u0027ll be discussing water."},{"Start":"00:06.645 ","End":"00:08.445","Text":"By the end of this section,"},{"Start":"00:08.445 ","End":"00:10.620","Text":"you\u0027ll be able to describe the properties"},{"Start":"00:10.620 ","End":"00:13.065","Text":"of water that are essential for maintaining life,"},{"Start":"00:13.065 ","End":"00:16.185","Text":"provide examples of water\u0027s cohesive properties,"},{"Start":"00:16.185 ","End":"00:19.005","Text":"explain why water is an excellent solvent,"},{"Start":"00:19.005 ","End":"00:21.030","Text":"and discuss the role of acids,"},{"Start":"00:21.030 ","End":"00:24.300","Text":"bases and buffers in homeostasis."},{"Start":"00:24.300 ","End":"00:28.920","Text":"Water has many properties that are essential for life."},{"Start":"00:28.920 ","End":"00:31.335","Text":"First, life on Earth began in water,"},{"Start":"00:31.335 ","End":"00:34.410","Text":"and has been evolving there for over 3 billion years."},{"Start":"00:34.410 ","End":"00:38.670","Text":"Cells are composed of 70-95 percent water."},{"Start":"00:38.670 ","End":"00:41.400","Text":"Most of an organism\u0027s cellular chemistry and"},{"Start":"00:41.400 ","End":"00:46.910","Text":"metabolism occur inside the watery contents of the cell\u0027s cytoplasm."},{"Start":"00:46.910 ","End":"00:50.570","Text":"Therefore, modern life still remains tied to water."},{"Start":"00:50.570 ","End":"00:54.620","Text":"Whether we need to live in an aqueous environment for at least part of our life."},{"Start":"00:54.620 ","End":"00:56.780","Text":"Or like mammals ourselves,"},{"Start":"00:56.780 ","End":"00:59.760","Text":"we can retain this environment internally."},{"Start":"00:59.800 ","End":"01:06.035","Text":"Some of the prominent life-supporting properties of water are as cohesive nature."},{"Start":"01:06.035 ","End":"01:08.480","Text":"Water is versatility as a solvent."},{"Start":"01:08.480 ","End":"01:13.655","Text":"It\u0027s temperature moderation, and the fact that ice floats over water."},{"Start":"01:13.655 ","End":"01:18.665","Text":"Whereas cohesive nature stems from the water molecules polarity."},{"Start":"01:18.665 ","End":"01:22.100","Text":"Each water molecule attracts other water molecules because of"},{"Start":"01:22.100 ","End":"01:26.070","Text":"the opposite charges between them forming hydrogen bonds."},{"Start":"01:26.070 ","End":"01:30.815","Text":"As we can see here, the oxygen atom has a net charge that\u0027s negative,"},{"Start":"01:30.815 ","End":"01:34.460","Text":"while the hydrogen atoms each have a net charge that is positive,"},{"Start":"01:34.460 ","End":"01:36.380","Text":"therefore they attract each other."},{"Start":"01:36.380 ","End":"01:39.530","Text":"The oxygen atom and the hydrogen atom"},{"Start":"01:39.530 ","End":"01:43.430","Text":"between all the molecules attract each other forming hydrogen bonds."},{"Start":"01:43.430 ","End":"01:47.060","Text":"These hydrogen bonds cause water molecules to stick together,"},{"Start":"01:47.060 ","End":"01:49.880","Text":"giving water a high surface tension."},{"Start":"01:49.880 ","End":"01:53.210","Text":"The definition of surface tension is the measure of how"},{"Start":"01:53.210 ","End":"01:57.230","Text":"difficult it is to stretch a regular surface of a liquid."},{"Start":"01:57.230 ","End":"02:00.290","Text":"One example for the biological dependence of"},{"Start":"02:00.290 ","End":"02:03.380","Text":"this property is in water transport in plants,"},{"Start":"02:03.380 ","End":"02:05.900","Text":"where this property causes water to be sucked"},{"Start":"02:05.900 ","End":"02:09.420","Text":"up from the root tips all the way to the leaves."},{"Start":"02:10.870 ","End":"02:14.135","Text":"Not only water molecules attract each other,"},{"Start":"02:14.135 ","End":"02:19.460","Text":"but they also are attracted by other polar molecules and ions."},{"Start":"02:19.460 ","End":"02:24.515","Text":"Hydrogen bonds allow ions and other polar molecules to dissolve in water."},{"Start":"02:24.515 ","End":"02:27.170","Text":"Therefore, water is an excellent solvent."},{"Start":"02:27.170 ","End":"02:29.480","Text":"Here we see an example of sodium chloride,"},{"Start":"02:29.480 ","End":"02:32.720","Text":"which is actually table salt being dissolved in water."},{"Start":"02:32.720 ","End":"02:34.940","Text":"We have here the sodium and the chloride."},{"Start":"02:34.940 ","End":"02:38.445","Text":"These 2 ions are positive and negative,"},{"Start":"02:38.445 ","End":"02:41.270","Text":"and the water molecules are surrounding them."},{"Start":"02:41.270 ","End":"02:44.980","Text":"We already know that the net charge of the oxygen\u0027s"},{"Start":"02:44.980 ","End":"02:52.670","Text":"negative and the charge of the hydrogen is positive."},{"Start":"02:52.670 ","End":"02:55.504","Text":"Therefore, what can we expect to happen?"},{"Start":"02:55.504 ","End":"03:01.310","Text":"The positive hydrogen atoms are attracted to the negative chlorine ions"},{"Start":"03:01.310 ","End":"03:07.805","Text":"and the negative oxygens are attracted to the sodium ion."},{"Start":"03:07.805 ","End":"03:10.705","Text":"This way the salt is dissolved in the water."},{"Start":"03:10.705 ","End":"03:16.985","Text":"The definition of solution is a liquid consisting of 2 or more substances evenly mixed."},{"Start":"03:16.985 ","End":"03:19.760","Text":"The dissolving agent is called the solvent."},{"Start":"03:19.760 ","End":"03:22.535","Text":"The dissolved substance is called the solute."},{"Start":"03:22.535 ","End":"03:24.110","Text":"When water is the solvent,"},{"Start":"03:24.110 ","End":"03:27.350","Text":"the result is called an aqueous solution."},{"Start":"03:27.350 ","End":"03:30.290","Text":"For our example, the dissolving agent,"},{"Start":"03:30.290 ","End":"03:32.330","Text":"the solvent would be water,"},{"Start":"03:32.330 ","End":"03:36.455","Text":"and the dissolved substance would be the sodium chloride."},{"Start":"03:36.455 ","End":"03:40.220","Text":"Therefore, we can divide all substances into 2 groups."},{"Start":"03:40.220 ","End":"03:42.260","Text":"Groups that are hydrophilic,"},{"Start":"03:42.260 ","End":"03:45.260","Text":"they describe ions or polar molecules that"},{"Start":"03:45.260 ","End":"03:48.620","Text":"interact well with other polar molecules, such as water."},{"Start":"03:48.620 ","End":"03:50.540","Text":"They are easily dissolved in water,"},{"Start":"03:50.540 ","End":"03:52.280","Text":"and that\u0027s why they\u0027re called hydrophilic."},{"Start":"03:52.280 ","End":"03:55.470","Text":"Hydro is water and philic is loving of."},{"Start":"03:55.470 ","End":"03:58.380","Text":"While other things may be hydrophobic."},{"Start":"03:58.380 ","End":"04:00.040","Text":"We have an example of oil."},{"Start":"04:00.040 ","End":"04:03.970","Text":"This word describes uncharged, non-polar molecules."},{"Start":"04:03.970 ","End":"04:07.000","Text":"They don\u0027t interact well with polar molecules such as water."},{"Start":"04:07.000 ","End":"04:10.390","Text":"We can now understand why this happens."},{"Start":"04:10.390 ","End":"04:13.555","Text":"The polar molecules are attracted, in fact,"},{"Start":"04:13.555 ","End":"04:17.050","Text":"to the differently charged ions or parts of"},{"Start":"04:17.050 ","End":"04:22.315","Text":"the water molecules that are polar and non-polar molecules cannot make this interaction,"},{"Start":"04:22.315 ","End":"04:24.850","Text":"and therefore they do not mix well with water."},{"Start":"04:24.850 ","End":"04:28.160","Text":"They are hydrophobic."},{"Start":"04:28.230 ","End":"04:31.690","Text":"Water also serves as a temperature moderator."},{"Start":"04:31.690 ","End":"04:34.360","Text":"The hydrogen bonds between water molecules"},{"Start":"04:34.360 ","End":"04:37.705","Text":"cause the water to have a very high heat capacity."},{"Start":"04:37.705 ","End":"04:41.600","Text":"That means that it takes a lot of added heat to raise this temperature."},{"Start":"04:41.600 ","End":"04:43.430","Text":"As the temperature rises,"},{"Start":"04:43.430 ","End":"04:48.350","Text":"the hydrogen bonds between water molecules continually break and form a new."},{"Start":"04:48.350 ","End":"04:51.935","Text":"This allows for the overall temperature to remain quite stable,"},{"Start":"04:51.935 ","End":"04:54.320","Text":"although a lot of energy is added to the system."},{"Start":"04:54.320 ","End":"04:58.860","Text":"That\u0027s why it takes so long to boil a pot of water."},{"Start":"04:58.960 ","End":"05:05.195","Text":"Earth\u0027s giant water supply causes temperatures to stay within limits that permit life."},{"Start":"05:05.195 ","End":"05:07.730","Text":"If we look at this island here,"},{"Start":"05:07.730 ","End":"05:11.015","Text":"the temperature between day and night varies greatly,"},{"Start":"05:11.015 ","End":"05:13.400","Text":"while the water\u0027s temperature is a lot more stable."},{"Start":"05:13.400 ","End":"05:17.345","Text":"Takes a longer time for the water to cool during the night and to heat during the day."},{"Start":"05:17.345 ","End":"05:21.950","Text":"The fact that the Earth has such a giant water supply means that"},{"Start":"05:21.950 ","End":"05:28.160","Text":"air Earth heats and cools a lot slower than it would if it would be all solid."},{"Start":"05:28.160 ","End":"05:35.000","Text":"This stability is what keeps the temperature to stay within the limits that permit life."},{"Start":"05:35.000 ","End":"05:40.070","Text":"Also evaporative cooling removes heat from the earth and from other organisms."},{"Start":"05:40.070 ","End":"05:42.260","Text":"While the sweat evaporates,"},{"Start":"05:42.260 ","End":"05:43.820","Text":"it takes a lot of energy,"},{"Start":"05:43.820 ","End":"05:46.520","Text":"as we said to break all those hydrogen bonds and that"},{"Start":"05:46.520 ","End":"05:50.180","Text":"energy actually is given by us and we let off the heat,"},{"Start":"05:50.180 ","End":"05:55.500","Text":"the excess heat, and we feel ourselves cooling nicely."},{"Start":"05:55.630 ","End":"06:00.500","Text":"Most substances, the differences between the states of matter between gas,"},{"Start":"06:00.500 ","End":"06:03.905","Text":"liquid and solid, are the density of the molecules."},{"Start":"06:03.905 ","End":"06:07.190","Text":"In gas we have the least dense molecules."},{"Start":"06:07.190 ","End":"06:08.660","Text":"They are furthest apart."},{"Start":"06:08.660 ","End":"06:10.595","Text":"In liquid they\u0027re already closer together,"},{"Start":"06:10.595 ","End":"06:13.425","Text":"and when it\u0027s solid, they\u0027re really compacted."},{"Start":"06:13.425 ","End":"06:18.770","Text":"Therefore in 1 cubic inch of gas,"},{"Start":"06:18.770 ","End":"06:24.020","Text":"we have less molecules than we do in 1 cubic inch of liquid,"},{"Start":"06:24.020 ","End":"06:28.780","Text":"than we have in 1 cubic inch of solid."},{"Start":"06:28.780 ","End":"06:33.005","Text":"Here, this means that if we weigh the mass,"},{"Start":"06:33.005 ","End":"06:35.405","Text":"we find that the gas is lighter than the liquid,"},{"Start":"06:35.405 ","End":"06:38.370","Text":"is lighter than the solid."},{"Start":"06:38.450 ","End":"06:41.745","Text":"On the contrary when water freezes,"},{"Start":"06:41.745 ","End":"06:50.105","Text":"the ice molecules form a rigid lattice structure due to the hydrogen bonds between them."},{"Start":"06:50.105 ","End":"06:53.180","Text":"What\u0027s special about this structure is that it\u0027s less"},{"Start":"06:53.180 ","End":"06:56.390","Text":"dense than the structure of liquid water."},{"Start":"06:56.390 ","End":"07:01.865","Text":"Therefore, if we take the same cap and fill it with liquid water,"},{"Start":"07:01.865 ","End":"07:04.766","Text":"or we take a cup and fill it with ice,"},{"Start":"07:04.766 ","End":"07:14.505","Text":"we define the water as a liquid is more dense than the lattice of the ice."},{"Start":"07:14.505 ","End":"07:20.055","Text":"That means that the water would weigh more than the ice."},{"Start":"07:20.055 ","End":"07:22.795","Text":"Therefore, ice floats over water."},{"Start":"07:22.795 ","End":"07:25.460","Text":"Since ice floats, ponds,"},{"Start":"07:25.460 ","End":"07:29.165","Text":"lakes, and even oceans, never freeze solid."},{"Start":"07:29.165 ","End":"07:31.625","Text":"Under the ice sheet,"},{"Start":"07:31.625 ","End":"07:36.590","Text":"we can always find liquid water and that allows marine life to survive."},{"Start":"07:36.590 ","End":"07:42.570","Text":"It also is what allowed life to evolve essentially in that water."},{"Start":"07:42.670 ","End":"07:46.670","Text":"Last but not least, the pH scale."},{"Start":"07:46.670 ","End":"07:50.850","Text":"The pH value is a measure of hydrogen ion."},{"Start":"07:52.310 ","End":"07:57.290","Text":"Is the measure of the hydrogen ion concentration in a solution."},{"Start":"07:57.290 ","End":"08:02.825","Text":"The pH scale is in inverse logarithm ranging between 0 and 14."},{"Start":"08:02.825 ","End":"08:06.430","Text":"This means that the lower the number is,"},{"Start":"08:06.430 ","End":"08:08.895","Text":"the more hydrogen ion we have."},{"Start":"08:08.895 ","End":"08:12.020","Text":"The fact that it\u0027s logarithm means that the difference"},{"Start":"08:12.020 ","End":"08:15.485","Text":"between each number would be times 10,"},{"Start":"08:15.485 ","End":"08:24.360","Text":"so 2 would have 10 times the hydrogen ion that we have in 3,"},{"Start":"08:24.360 ","End":"08:27.375","Text":"for example, and so forth."},{"Start":"08:27.375 ","End":"08:32.460","Text":"Any value is below 7 are acidic,"},{"Start":"08:32.460 ","End":"08:34.700","Text":"lower number we get, of course,"},{"Start":"08:34.700 ","End":"08:36.815","Text":"the more the stronger the acid is."},{"Start":"08:36.815 ","End":"08:40.910","Text":"Values above 7 are alkaline or basic."},{"Start":"08:40.910 ","End":"08:43.775","Text":"The most basic thing we have here is the drain cleaner,"},{"Start":"08:43.775 ","End":"08:49.530","Text":"which you would not want to touch or the strong acid."},{"Start":"08:49.840 ","End":"08:53.240","Text":"These properties of water are intimately collected with"},{"Start":"08:53.240 ","End":"08:56.890","Text":"the biochemical and physical processes performed by living organisms."},{"Start":"08:56.890 ","End":"08:59.915","Text":"Life would be very difficult if these properties were altered,"},{"Start":"08:59.915 ","End":"09:01.715","Text":"if it could exist at all."},{"Start":"09:01.715 ","End":"09:08.705","Text":"Therefore, pH value is highly regulated in living organisms through homeostasis."},{"Start":"09:08.705 ","End":"09:11.600","Text":"Acids and bases can change the pH values,"},{"Start":"09:11.600 ","End":"09:14.840","Text":"but buffers tend to moderate the change they cause."},{"Start":"09:14.840 ","End":"09:19.220","Text":"For example, in our blood we have buffers making sure that even if"},{"Start":"09:19.220 ","End":"09:23.975","Text":"acidic or basic solutions get into our blood,"},{"Start":"09:23.975 ","End":"09:27.300","Text":"they won\u0027t make such a dramatic change."},{"Start":"09:28.600 ","End":"09:33.200","Text":"We\u0027ve described the properties of water that are essential for maintaining life."},{"Start":"09:33.200 ","End":"09:36.920","Text":"We\u0027ve provided examples of water\u0027s cohesive properties."},{"Start":"09:36.920 ","End":"09:39.695","Text":"We explain why water is an excellent solvent,"},{"Start":"09:39.695 ","End":"09:41.870","Text":"and we\u0027ve discussed the roles of acids,"},{"Start":"09:41.870 ","End":"09:45.420","Text":"bases and buffers and homeostasis."}],"ID":24142},{"Watched":false,"Name":"Carbon Based Molecules","Duration":"6m 23s","ChapterTopicVideoID":23255,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.700","Text":"Hey there. We\u0027re learning about"},{"Start":"00:02.700 ","End":"00:06.900","Text":"the chemical foundation of life and today we\u0027ll study carbon."},{"Start":"00:06.900 ","End":"00:08.400","Text":"By the end of this section,"},{"Start":"00:08.400 ","End":"00:11.370","Text":"you\u0027ll be able to explain why carbon is so important for"},{"Start":"00:11.370 ","End":"00:17.050","Text":"life and describe the role of functional groups in biological molecules."},{"Start":"00:18.830 ","End":"00:21.885","Text":"All those cells are mostly made of water."},{"Start":"00:21.885 ","End":"00:26.955","Text":"The remainder of the cell consists almost only of carbon-based molecules."},{"Start":"00:26.955 ","End":"00:32.280","Text":"The unique properties of carbon make it a central part of biological molecules."},{"Start":"00:32.280 ","End":"00:34.795","Text":"The definition of organic chemistry,"},{"Start":"00:34.795 ","End":"00:38.400","Text":"is the study of these carbon compounds."},{"Start":"00:39.050 ","End":"00:43.415","Text":"Carbon has 4 electrons in its outermost shell."},{"Start":"00:43.415 ","End":"00:46.130","Text":"Therefore, it can form 4 bonds,"},{"Start":"00:46.130 ","End":"00:48.985","Text":"1, 2, 3 and 4."},{"Start":"00:48.985 ","End":"00:51.495","Text":"Carbon can bind to oxygen,"},{"Start":"00:51.495 ","End":"00:54.230","Text":"hydrogen and nitrogen covalently to form"},{"Start":"00:54.230 ","End":"00:57.785","Text":"the many molecules important for cellular function."},{"Start":"00:57.785 ","End":"01:00.953","Text":"The carbon atom is very versatile,"},{"Start":"01:00.953 ","End":"01:04.430","Text":"it can bind to itself in an almost limitless combination of"},{"Start":"01:04.430 ","End":"01:09.635","Text":"straight or branched chains and rings and form an infinite number of compounds."},{"Start":"01:09.635 ","End":"01:12.130","Text":"Here we see an example of a ring."},{"Start":"01:12.130 ","End":"01:18.875","Text":"Hydrocarbons are organic molecules consisting entirely of carbon and hydrogen."},{"Start":"01:18.875 ","End":"01:22.035","Text":"Here we have a molecule of methane,"},{"Start":"01:22.035 ","End":"01:28.165","Text":"we have the carbon in the center and 4 atoms of hydrogen."},{"Start":"01:28.165 ","End":"01:31.775","Text":"Hydrocarbons can also form long chains."},{"Start":"01:31.775 ","End":"01:34.850","Text":"These are called aliphatic hydrocarbons and"},{"Start":"01:34.850 ","End":"01:37.820","Text":"they consist of linear chains of carbon atoms."},{"Start":"01:37.820 ","End":"01:41.880","Text":"Here we see many carbon atoms attached covalently to each other"},{"Start":"01:41.880 ","End":"01:46.175","Text":"and we can also see hydrogen atoms attached to each of these carbons."},{"Start":"01:46.175 ","End":"01:48.866","Text":"The carbon here has actually 4 connections,"},{"Start":"01:48.866 ","End":"01:51.920","Text":"it\u0027s connected to 2 hydrogen atoms and it\u0027s also"},{"Start":"01:51.920 ","End":"01:56.650","Text":"connected in the chain to the carbons before and after it."},{"Start":"01:56.650 ","End":"02:00.415","Text":"When carbon forms single bonds with other atoms,"},{"Start":"02:00.415 ","End":"02:02.965","Text":"the shape is tetrahedral,"},{"Start":"02:02.965 ","End":"02:05.635","Text":"this shape is called tetrahedral."},{"Start":"02:05.635 ","End":"02:07.855","Text":"Example here is methane."},{"Start":"02:07.855 ","End":"02:10.465","Text":"When 2 carbon atoms form a double bond,"},{"Start":"02:10.465 ","End":"02:12.145","Text":"the shape is planar or flat,"},{"Start":"02:12.145 ","End":"02:15.260","Text":"like in this ethane molecule."},{"Start":"02:15.650 ","End":"02:21.280","Text":"Single bonds like those found in ethane are able to rotate around."},{"Start":"02:21.280 ","End":"02:22.675","Text":"Here we have 2 carbons,"},{"Start":"02:22.675 ","End":"02:24.850","Text":"they can rotate around each other."},{"Start":"02:24.850 ","End":"02:29.380","Text":"The double bonds like those found in ethene here,"},{"Start":"02:29.380 ","End":"02:31.630","Text":"we just saw before, they can\u0027t rotate,"},{"Start":"02:31.630 ","End":"02:33.940","Text":"so the atoms on either side are locked in place."},{"Start":"02:33.940 ","End":"02:37.470","Text":"That\u0027s why they form this planar shape."},{"Start":"02:37.470 ","End":"02:42.870","Text":"Hydrocarbon rings consists of closed rings of carbon atoms."},{"Start":"02:43.230 ","End":"02:46.915","Text":"Carbon can form 5 and 6 membered rings."},{"Start":"02:46.915 ","End":"02:51.045","Text":"Here we have 5 membered ring and here\u0027s 6 membered ring."},{"Start":"02:51.045 ","End":"02:55.130","Text":"Single or double bonds may connect the carbon atoms in the ring."},{"Start":"02:55.130 ","End":"02:59.315","Text":"Here we have an example of some of the carbon atoms connected with a double bond,"},{"Start":"02:59.315 ","End":"03:02.165","Text":"while others are connected with a single bond only."},{"Start":"03:02.165 ","End":"03:06.200","Text":"Nitrogen may substitute for carbon in the ring."},{"Start":"03:06.200 ","End":"03:10.310","Text":"Functional groups are groups of atoms that"},{"Start":"03:10.310 ","End":"03:14.135","Text":"confer specific properties to the hydrocarbon molecule."},{"Start":"03:14.135 ","End":"03:18.910","Text":"These groups define their overall chemical characteristics and function."},{"Start":"03:18.910 ","End":"03:20.895","Text":"We\u0027ll give here some examples."},{"Start":"03:20.895 ","End":"03:24.830","Text":"Hydroxyl for example, here we have the molecule and"},{"Start":"03:24.830 ","End":"03:29.300","Text":"this here is the oxygen and hydrogen is the hydroxyl."},{"Start":"03:29.300 ","End":"03:33.450","Text":"The property that it gives the molecule is polar."},{"Start":"03:33.460 ","End":"03:36.560","Text":"This is another functional group called methyl."},{"Start":"03:36.560 ","End":"03:41.675","Text":"Here we have our molecule or hydrocarbon and at the edge we have a carbon"},{"Start":"03:41.675 ","End":"03:47.835","Text":"connected to 3 hydrogen atoms, H_3."},{"Start":"03:47.835 ","End":"03:50.870","Text":"This is a nonpolar functional group,"},{"Start":"03:50.870 ","End":"03:54.325","Text":"turning the molecule to be nonpolar."},{"Start":"03:54.325 ","End":"04:01.305","Text":"Carbonyl, the carbonyl functional group connect 2 macromolecules,"},{"Start":"04:01.305 ","End":"04:05.255","Text":"2 hydrocarbons and we have here a double bond to oxygen."},{"Start":"04:05.255 ","End":"04:08.885","Text":"This causes the molecule to be polar."},{"Start":"04:08.885 ","End":"04:13.770","Text":"The carboxyl functional group is this structure"},{"Start":"04:13.770 ","End":"04:17.870","Text":"attached to hydrocarbon and it is charged,"},{"Start":"04:17.870 ","End":"04:20.360","Text":"it\u0027s ionized to release a proton."},{"Start":"04:20.360 ","End":"04:25.490","Text":"This is a hydrogen ion and this causes the molecule to be acidic."},{"Start":"04:25.490 ","End":"04:28.520","Text":"This functional group, the carboxyl,"},{"Start":"04:28.520 ","End":"04:31.070","Text":"is charged and it accepts protons."},{"Start":"04:31.070 ","End":"04:34.245","Text":"Thus the molecule gets basic properties."},{"Start":"04:34.245 ","End":"04:38.235","Text":"The phosphate group, this here."},{"Start":"04:38.235 ","End":"04:41.270","Text":"It\u0027s charged, it\u0027s ionized and it releases a proton."},{"Start":"04:41.270 ","End":"04:45.205","Text":"Again, this causes the molecule to be acidic."},{"Start":"04:45.205 ","End":"04:49.170","Text":"Sulfhydryl, our last example for today."},{"Start":"04:49.170 ","End":"04:51.905","Text":"Here we have sulfur and hydrogen."},{"Start":"04:51.905 ","End":"04:55.445","Text":"It again causes the molecule to be polar."},{"Start":"04:55.445 ","End":"05:00.260","Text":"Hydrogen bonds are weak bonds between slightly positively charged hydrogen atoms,"},{"Start":"05:00.260 ","End":"05:02.855","Text":"to slightly negatively charged atoms in another molecule."},{"Start":"05:02.855 ","End":"05:05.975","Text":"Here we have hydrogen bonds between water molecules."},{"Start":"05:05.975 ","End":"05:10.025","Text":"Hydrogen bonds can also be formed between functional groups."},{"Start":"05:10.025 ","End":"05:13.025","Text":"They\u0027re very important to the function of very macromolecules."},{"Start":"05:13.025 ","End":"05:18.370","Text":"They help them to fold properly into and maintain the appropriate shape for functioning."},{"Start":"05:18.370 ","End":"05:23.195","Text":"Hydrogen bonds are also involved in various recognition processes,"},{"Start":"05:23.195 ","End":"05:28.590","Text":"such as DNA complementary base pairing and the binding of an enzyme to its substrate."},{"Start":"05:28.590 ","End":"05:30.980","Text":"Here\u0027s the example of a DNA molecule."},{"Start":"05:30.980 ","End":"05:36.845","Text":"We have here the sugar phosphate backbone on both sides of this double helix."},{"Start":"05:36.845 ","End":"05:38.690","Text":"Inside we have the basis."},{"Start":"05:38.690 ","End":"05:40.490","Text":"What holds these bases together?"},{"Start":"05:40.490 ","End":"05:42.245","Text":"What pairs them?"},{"Start":"05:42.245 ","End":"05:45.290","Text":"We can see here the molecular structure,"},{"Start":"05:45.290 ","End":"05:50.845","Text":"here we have the sugar phosphate backbone on both sides and we have the bases."},{"Start":"05:50.845 ","End":"05:53.530","Text":"This is the sugar-phosphate backbone."},{"Start":"05:54.170 ","End":"05:57.120","Text":"We have here, the inner bases."},{"Start":"05:57.120 ","End":"06:00.180","Text":"Here are the bases of the left strand."},{"Start":"06:00.180 ","End":"06:02.355","Text":"Here are the bases of the right strand."},{"Start":"06:02.355 ","End":"06:05.770","Text":"What connects them is actually hydrogen bonds,"},{"Start":"06:05.770 ","End":"06:07.910","Text":"that really holds everything together."},{"Start":"06:07.910 ","End":"06:11.400","Text":"You\u0027ll see this is what holds the basis together."},{"Start":"06:11.560 ","End":"06:15.515","Text":"We explain why carbon is so important for life."},{"Start":"06:15.515 ","End":"06:18.500","Text":"We also describe the role of some functional groups in"},{"Start":"06:18.500 ","End":"06:22.470","Text":"biological molecules. Thanks for listening."}],"ID":24143},{"Watched":false,"Name":"Exercise 1","Duration":"1m 5s","ChapterTopicVideoID":23256,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.070 ","End":"00:04.980","Text":"Hi. Now that we\u0027ve studied the chemical foundation of life,"},{"Start":"00:04.980 ","End":"00:08.710","Text":"let\u0027s try to answer a few questions about the subject."},{"Start":"00:08.770 ","End":"00:14.580","Text":"Radon\u0027s atomic number is 86 and its mass number 222."},{"Start":"00:14.580 ","End":"00:17.740","Text":"How many neutrons does it have?"},{"Start":"00:17.780 ","End":"00:21.165","Text":"We know this much from the periodic table."},{"Start":"00:21.165 ","End":"00:25.560","Text":"The atomic number is the number of protons in an atom\u0027s nucleus so we can tell"},{"Start":"00:25.560 ","End":"00:29.669","Text":"right away then atom of radon contains 86 protons."},{"Start":"00:29.669 ","End":"00:31.470","Text":"Now the mass number here,"},{"Start":"00:31.470 ","End":"00:35.489","Text":"222, is the total number of protons and neutrons."},{"Start":"00:35.489 ","End":"00:39.825","Text":"Therefore, in order to find the number of neutrons we have to subtract"},{"Start":"00:39.825 ","End":"00:45.945","Text":"the number of protons from the atomic mass,"},{"Start":"00:45.945 ","End":"00:53.120","Text":"which is 222 minus 86."},{"Start":"00:53.120 ","End":"00:58.625","Text":"That is 136 neutrons."},{"Start":"00:58.625 ","End":"01:00.635","Text":"Therefore, the answer is d,"},{"Start":"01:00.635 ","End":"01:03.245","Text":"a 136, not a,"},{"Start":"01:03.245 ","End":"01:05.910","Text":"not b or c."}],"ID":24144},{"Watched":false,"Name":"Exercise 2","Duration":"1m 29s","ChapterTopicVideoID":23257,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.440 ","End":"00:04.740","Text":"Variations in the number of neutrons in the atom\u0027s nuclei are called?"},{"Start":"00:04.740 ","End":"00:07.050","Text":"A, charged protons, b,"},{"Start":"00:07.050 ","End":"00:08.400","Text":"anions, c,"},{"Start":"00:08.400 ","End":"00:11.535","Text":"isotopes, or d, neutral atoms."},{"Start":"00:11.535 ","End":"00:14.220","Text":"Let\u0027s take a look at the structure of an atom."},{"Start":"00:14.220 ","End":"00:18.435","Text":"In the nucleus, we have positively charged protons,"},{"Start":"00:18.435 ","End":"00:21.990","Text":"uncharged neutrons, and orbiting these,"},{"Start":"00:21.990 ","End":"00:26.410","Text":"we have negatively charged electrons."},{"Start":"00:26.540 ","End":"00:29.150","Text":"A, charged protons."},{"Start":"00:29.150 ","End":"00:32.270","Text":"Well, all protons are charged as we can see here."},{"Start":"00:32.270 ","End":"00:34.220","Text":"What are anions?"},{"Start":"00:34.220 ","End":"00:40.685","Text":"These are atoms with extra electrons orbiting,"},{"Start":"00:40.685 ","End":"00:42.800","Text":"giving the atom a negative charge."},{"Start":"00:42.800 ","End":"00:45.215","Text":"We have here 2 protons."},{"Start":"00:45.215 ","End":"00:48.349","Text":"These 2 electrons give a neutral atom,"},{"Start":"00:48.349 ","End":"00:54.115","Text":"and adding more electrons will give us a negative charge of minus 2."},{"Start":"00:54.115 ","End":"00:57.610","Text":"That\u0027s what anions are."},{"Start":"00:59.110 ","End":"01:05.525","Text":"The neutral atoms would just be the same atom without these extra electrons."},{"Start":"01:05.525 ","End":"01:08.170","Text":"Therefore, we can rule out a,"},{"Start":"01:08.170 ","End":"01:12.245","Text":"b, and d. What are isotopes?"},{"Start":"01:12.245 ","End":"01:17.705","Text":"Isotopes are actually atoms with extra neutrons."},{"Start":"01:17.705 ","End":"01:19.985","Text":"If we would change the number of protons,"},{"Start":"01:19.985 ","End":"01:22.280","Text":"we would get a different element."},{"Start":"01:22.280 ","End":"01:25.785","Text":"Adding neutrons gives us different isotopes."},{"Start":"01:25.785 ","End":"01:29.260","Text":"So the answer is c, isotopes."}],"ID":24145},{"Watched":false,"Name":"Exercise 3","Duration":"58s","ChapterTopicVideoID":23258,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.060","Text":"The nucleus of an atom typically contains,"},{"Start":"00:03.060 ","End":"00:06.240","Text":"A, electrons and neutrons, B,"},{"Start":"00:06.240 ","End":"00:08.055","Text":"only neutrons, C,"},{"Start":"00:08.055 ","End":"00:09.570","Text":"only protons, D,"},{"Start":"00:09.570 ","End":"00:13.995","Text":"protons and neutrons, E, protons and electrons."},{"Start":"00:13.995 ","End":"00:16.780","Text":"Let\u0027s look at the structure of the atom."},{"Start":"00:17.120 ","End":"00:21.690","Text":"We can see that the nucleus contains neutrons and"},{"Start":"00:21.690 ","End":"00:26.625","Text":"protons while the electrons are orbiting these on the outskirts."},{"Start":"00:26.625 ","End":"00:30.075","Text":"The correct answer will be protons and neutrons,"},{"Start":"00:30.075 ","End":"00:34.660","Text":"not electrons and neutrons since the electrons are not in the nucleus."},{"Start":"00:34.660 ","End":"00:38.765","Text":"B, only neutrons is wrong since we always have protons."},{"Start":"00:38.765 ","End":"00:42.410","Text":"C, only protons would not be correct as"},{"Start":"00:42.410 ","End":"00:46.040","Text":"we almost always have neutrons except for the hydrogen,"},{"Start":"00:46.040 ","End":"00:49.625","Text":"which is specifically except for the hydrogen atom."},{"Start":"00:49.625 ","End":"00:51.590","Text":"Or E, protons and electrons,"},{"Start":"00:51.590 ","End":"00:57.840","Text":"as we said electrons orbit the atom and are not in the nucleus."}],"ID":24146},{"Watched":false,"Name":"Exercise 4","Duration":"2m 3s","ChapterTopicVideoID":23259,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.103","Text":"Atomic mass is the A,"},{"Start":"00:03.103 ","End":"00:04.695","Text":"weight of an atom."},{"Start":"00:04.695 ","End":"00:06.765","Text":"B, number of protons."},{"Start":"00:06.765 ","End":"00:09.764","Text":"C, number of protons and electrons."},{"Start":"00:09.764 ","End":"00:12.404","Text":"D, number of protons and neutrons,"},{"Start":"00:12.404 ","End":"00:15.810","Text":"or E, number of neutrons and electrons."},{"Start":"00:15.810 ","End":"00:18.225","Text":"What is the atomic mass?"},{"Start":"00:18.225 ","End":"00:20.865","Text":"Let\u0027s have a look at the structure of the atom."},{"Start":"00:20.865 ","End":"00:25.650","Text":"In the nucleus, we have the neutrons and protons and in the outskirts,"},{"Start":"00:25.650 ","End":"00:29.130","Text":"we have electrons orbiting the nucleus."},{"Start":"00:29.130 ","End":"00:31.379","Text":"As for the mass,"},{"Start":"00:31.379 ","End":"00:35.220","Text":"the proton and the neutron are very similar in mass,"},{"Start":"00:35.220 ","End":"00:37.400","Text":"each of them approximately 1 atomic mass"},{"Start":"00:37.400 ","End":"00:41.270","Text":"unit while the electron is so light that for us,"},{"Start":"00:41.270 ","End":"00:44.285","Text":"virtually, we can consider it to be weightless."},{"Start":"00:44.285 ","End":"00:46.790","Text":"Therefore, when we want to know what the weight of an atom is,"},{"Start":"00:46.790 ","End":"00:51.905","Text":"we need to count the number of protons and neutrons which are usually equal."},{"Start":"00:51.905 ","End":"00:54.790","Text":"Calcium, for example, if the atomic number is 20,"},{"Start":"00:54.790 ","End":"00:57.845","Text":"meaning we have 20 protons in the nucleus."},{"Start":"00:57.845 ","End":"01:00.680","Text":"The atomic mass will be 40."},{"Start":"01:00.680 ","End":"01:04.810","Text":"Now you can ask why is it 40.078?"},{"Start":"01:04.810 ","End":"01:10.340","Text":"That\u0027s because some of the atoms have extra neutrons,"},{"Start":"01:10.340 ","End":"01:13.430","Text":"an extra neutron, even 2 in some cases,"},{"Start":"01:13.430 ","End":"01:15.050","Text":"these are called isotopes."},{"Start":"01:15.050 ","End":"01:16.715","Text":"These are naturally occurring,"},{"Start":"01:16.715 ","End":"01:18.140","Text":"since they occur naturally,"},{"Start":"01:18.140 ","End":"01:21.360","Text":"if you take the average weight of calcium in nature,"},{"Start":"01:21.360 ","End":"01:23.930","Text":"it can be a little bit higher than 40."},{"Start":"01:23.930 ","End":"01:29.210","Text":"The atomic mass is in fact the weight of an element,"},{"Start":"01:29.210 ","End":"01:33.935","Text":"not the number of protons and electrons."},{"Start":"01:33.935 ","End":"01:36.305","Text":"Electrons are virtually weightless."},{"Start":"01:36.305 ","End":"01:39.185","Text":"Number of protons and neutrons is"},{"Start":"01:39.185 ","End":"01:43.430","Text":"a tricky answer because the number of protons and neutrons"},{"Start":"01:43.430 ","End":"01:46.910","Text":"does give us the atomic mass but the atomic mass is in fact"},{"Start":"01:46.910 ","End":"01:51.290","Text":"the weight of the element and not the number of protons and neutrons."},{"Start":"01:51.290 ","End":"01:54.620","Text":"E, number of neutrons and electrons, of course,"},{"Start":"01:54.620 ","End":"01:57.350","Text":"is wrong too and as we have mentioned, again,"},{"Start":"01:57.350 ","End":"02:03.180","Text":"electrons are virtually weightless and we left out the protons in its answer."}],"ID":24147},{"Watched":false,"Name":"Exercise 5","Duration":"1m 16s","ChapterTopicVideoID":23260,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.875","Text":"An acidic solution has a high concentration of a, hydroxide ions."},{"Start":"00:05.875 ","End":"00:07.365","Text":"B, hydrogen ions."},{"Start":"00:07.365 ","End":"00:10.180","Text":"C, carboxylic aids."},{"Start":"00:10.180 ","End":"00:12.435","Text":"Or d, sodium."},{"Start":"00:12.435 ","End":"00:15.330","Text":"What exactly is an acidic solution?"},{"Start":"00:15.330 ","End":"00:19.993","Text":"The acidity of the solution is measured by what we call pH,"},{"Start":"00:19.993 ","End":"00:23.580","Text":"while p stands for the decimal cologarithm of,"},{"Start":"00:23.580 ","End":"00:32.640","Text":"so pH is the decimal cologarithm base"},{"Start":"00:32.640 ","End":"00:37.817","Text":"10 of the amount of hydrogen ions."},{"Start":"00:37.817 ","End":"00:42.210","Text":"which means the more hydrogen ions we\u0027re going to have,"},{"Start":"00:42.210 ","End":"00:46.955","Text":"the more this whole thing will be bigger."},{"Start":"00:46.955 ","End":"00:49.100","Text":"Since you have a minus over here,"},{"Start":"00:49.100 ","End":"00:51.905","Text":"the pH will be lower and lower."},{"Start":"00:51.905 ","End":"00:58.820","Text":"In a low pH, we have many hydrogen ions,"},{"Start":"00:58.820 ","End":"01:02.510","Text":"while here we have a lot less, say here."},{"Start":"01:02.510 ","End":"01:09.265","Text":"Here we don\u0027t have it all, we actually have OH, hydroxide ions."},{"Start":"01:09.265 ","End":"01:13.925","Text":"Therefore, the answer is b, hydrogen ions."},{"Start":"01:13.925 ","End":"01:16.440","Text":"The rest of them are wrong."}],"ID":24148},{"Watched":false,"Name":"Exercise 6","Duration":"1m 34s","ChapterTopicVideoID":23261,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.720","Text":"When 2 atoms share electrons, A,"},{"Start":"00:03.720 ","End":"00:05.160","Text":"an ion is formed,"},{"Start":"00:05.160 ","End":"00:08.490","Text":"B, a covalent bond is formed, C,"},{"Start":"00:08.490 ","End":"00:11.100","Text":"an ionic bond is formed, D,"},{"Start":"00:11.100 ","End":"00:13.185","Text":"a hydrogen bond is formed,"},{"Start":"00:13.185 ","End":"00:18.840","Text":"E, these are some example of van der Waals interactions."},{"Start":"00:18.840 ","End":"00:22.780","Text":"Let\u0027s take a look at it. What\u0027s an ion?"},{"Start":"00:22.970 ","End":"00:27.830","Text":"Well, an ion is a positively or negatively charged atom,"},{"Start":"00:27.830 ","End":"00:32.065","Text":"so that obviously has nothing to do with sharing electrons."},{"Start":"00:32.065 ","End":"00:38.360","Text":"When these 2 atoms positively and negatively charged meet each other,"},{"Start":"00:38.360 ","End":"00:40.625","Text":"they form what we call it an ionic bond,"},{"Start":"00:40.625 ","End":"00:42.980","Text":"which is like taking 2 magnets with"},{"Start":"00:42.980 ","End":"00:46.250","Text":"opposite charges and having them connect to each other."},{"Start":"00:46.250 ","End":"00:51.990","Text":"That again, has nothing to do with sharing electrons. You can cross that out."},{"Start":"00:52.390 ","End":"00:56.240","Text":"Hydrogen bond is a very weak bond between"},{"Start":"00:56.240 ","End":"00:58.765","Text":"slightly positively charged hydrogen atoms and"},{"Start":"00:58.765 ","End":"01:01.715","Text":"suddenly negatively charged atoms in another molecule."},{"Start":"01:01.715 ","End":"01:04.025","Text":"Also wrong."},{"Start":"01:04.025 ","End":"01:08.225","Text":"A van der Waals interaction is a very weak interaction between molecules"},{"Start":"01:08.225 ","End":"01:12.830","Text":"due to temporary charges attracting atoms that are very close together."},{"Start":"01:12.830 ","End":"01:15.200","Text":"This also has nothing to do with sharing electrons."},{"Start":"01:15.200 ","End":"01:16.595","Text":"We can cross this one out."},{"Start":"01:16.595 ","End":"01:18.230","Text":"A covalent bond,"},{"Start":"01:18.230 ","End":"01:19.740","Text":"on the other hand,"},{"Start":"01:19.740 ","End":"01:22.845","Text":"is when atoms share electrons."},{"Start":"01:22.845 ","End":"01:24.743","Text":"This bond is a very strong bond."},{"Start":"01:24.743 ","End":"01:26.655","Text":"It\u0027s hard to separate."},{"Start":"01:26.655 ","End":"01:29.175","Text":"Our answer is B."},{"Start":"01:29.175 ","End":"01:31.515","Text":"When 2 atoms share electrons,"},{"Start":"01:31.515 ","End":"01:34.630","Text":"a covalent bond is formed."}],"ID":24149},{"Watched":false,"Name":"Exercise 7","Duration":"1m 31s","ChapterTopicVideoID":23262,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.090","Text":"Which bond represents a weak chemical bond?"},{"Start":"00:03.090 ","End":"00:06.105","Text":"A, hydrogen bond, B,"},{"Start":"00:06.105 ","End":"00:08.685","Text":"non-polar covalent bond, C,"},{"Start":"00:08.685 ","End":"00:13.380","Text":"covalent bond, D, Polar covalent bond."},{"Start":"00:13.380 ","End":"00:16.860","Text":"Well, hydrogen bonds are weak bonds between"},{"Start":"00:16.860 ","End":"00:19.305","Text":"slightly positively charged hydrogen atoms"},{"Start":"00:19.305 ","End":"00:22.470","Text":"to slightly negatively charged atoms in another molecule."},{"Start":"00:22.470 ","End":"00:25.485","Text":"Therefore, this is our correct answer."},{"Start":"00:25.485 ","End":"00:28.810","Text":"What about all these covalent bonds?"},{"Start":"00:29.330 ","End":"00:32.100","Text":"What is a covalent bond?"},{"Start":"00:32.100 ","End":"00:36.320","Text":"This is when atoms actually share electrons."},{"Start":"00:36.320 ","End":"00:39.445","Text":"The electrons can move between the whole molecule now."},{"Start":"00:39.445 ","End":"00:42.165","Text":"It a very strong bond."},{"Start":"00:42.165 ","End":"00:45.440","Text":"When the electrons are shared equally,"},{"Start":"00:45.440 ","End":"00:48.050","Text":"we call it a non-polar covalent bond."},{"Start":"00:48.050 ","End":"00:52.430","Text":"For example, here we have a polar covalent bond because the oxygen"},{"Start":"00:52.430 ","End":"00:57.290","Text":"has a lot more protons in its nucleus than the hydrogens."},{"Start":"00:57.290 ","End":"01:04.490","Text":"Therefore, the oxygen atom pulls the electrons stronger than the hydrogen atoms do."},{"Start":"01:04.490 ","End":"01:10.580","Text":"The net charge here is negative while the net charge here tends to be positive."},{"Start":"01:10.580 ","End":"01:14.510","Text":"This we call a polar covalent bond because along this water molecule,"},{"Start":"01:14.510 ","End":"01:21.860","Text":"we have a pole minus negatively charged side and a plus positively charged side,"},{"Start":"01:21.860 ","End":"01:24.695","Text":"and all these covalent bonds are actually very strong."},{"Start":"01:24.695 ","End":"01:27.755","Text":"Since you asked about a weak chemical bond,"},{"Start":"01:27.755 ","End":"01:32.110","Text":"we can say that the answer is A, hydrogen bond."}],"ID":24150},{"Watched":false,"Name":"Exercise 8","Duration":"1m 57s","ChapterTopicVideoID":23263,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.660","Text":"Which of the following statements is true?"},{"Start":"00:03.660 ","End":"00:07.215","Text":"A, ionic bond is the strongest bond."},{"Start":"00:07.215 ","End":"00:09.240","Text":"What\u0027s an ionic bond?"},{"Start":"00:09.240 ","End":"00:13.680","Text":"This is when we have 2 ions negatively"},{"Start":"00:13.680 ","End":"00:15.540","Text":"and positively charged meeting each"},{"Start":"00:15.540 ","End":"00:18.435","Text":"other and they are attracted to each other, just like magnets."},{"Start":"00:18.435 ","End":"00:20.445","Text":"Now this bond isn\u0027t so weak,"},{"Start":"00:20.445 ","End":"00:26.145","Text":"but can be very easily broken."},{"Start":"00:26.145 ","End":"00:32.170","Text":"For example, if you take this table salt and pour it into glass of water,"},{"Start":"00:33.560 ","End":"00:36.660","Text":"so know it\u0027s not the strongest bond."},{"Start":"00:36.660 ","End":"00:43.415","Text":"B, hydrogen bonds are responsible for a cohesive and adhesive properties of water."},{"Start":"00:43.415 ","End":"00:48.020","Text":"Hydrogen bonds are very weak bond between"},{"Start":"00:48.020 ","End":"00:50.720","Text":"slightly positively charged hydrogen atoms in"},{"Start":"00:50.720 ","End":"00:54.800","Text":"1 molecule to slightly negatively charged atoms and another molecule."},{"Start":"00:54.800 ","End":"00:56.870","Text":"In this example, another molecule of water,"},{"Start":"00:56.870 ","End":"00:59.600","Text":"we have the oxygen atom,"},{"Start":"00:59.600 ","End":"01:02.330","Text":"which is slightly negatively charged."},{"Start":"01:02.330 ","End":"01:07.745","Text":"These bonds are in fact responsible for the cohesive and adhesive properties of water."},{"Start":"01:07.745 ","End":"01:10.580","Text":"It helps water stick together and"},{"Start":"01:10.580 ","End":"01:13.460","Text":"why it\u0027s hard for us to break the surface of water and for related enough,"},{"Start":"01:13.460 ","End":"01:18.625","Text":"you can actually walk on water as these insect do."},{"Start":"01:18.625 ","End":"01:21.845","Text":"Yes, this is the correct answer. It\u0027s true."},{"Start":"01:21.845 ","End":"01:24.710","Text":"Let\u0027s look at the other statements before we go on."},{"Start":"01:24.710 ","End":"01:28.520","Text":"Van der Waals interactions are the strongest bond."},{"Start":"01:28.520 ","End":"01:33.290","Text":"Van der Waals interactions are in fact very weak interactions between molecules"},{"Start":"01:33.290 ","End":"01:38.165","Text":"due to temporary charges attracting atoms that are very close together."},{"Start":"01:38.165 ","End":"01:41.105","Text":"These are very weak bonds and this is the wrong answer."},{"Start":"01:41.105 ","End":"01:44.255","Text":"D, covalent bonds are the weakest bond."},{"Start":"01:44.255 ","End":"01:46.700","Text":"Covalent bonds are actually the strongest bond and"},{"Start":"01:46.700 ","End":"01:49.130","Text":"they are due to sharing of electrons between atoms."},{"Start":"01:49.130 ","End":"01:50.810","Text":"They\u0027re very hard to break."},{"Start":"01:50.810 ","End":"01:52.550","Text":"E, none of the above is true,"},{"Start":"01:52.550 ","End":"01:54.080","Text":"since we have a true answer,"},{"Start":"01:54.080 ","End":"01:57.540","Text":"we can mark our answer to be b."}],"ID":24151},{"Watched":false,"Name":"Exercise 9","Duration":"1m 34s","ChapterTopicVideoID":23264,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.670","Text":"When a Beta is added to a solution,"},{"Start":"00:02.670 ","End":"00:05.460","Text":"the pH should; A, decrease,"},{"Start":"00:05.460 ","End":"00:07.815","Text":"B, increase, C,"},{"Start":"00:07.815 ","End":"00:09.705","Text":"stay the same, D,"},{"Start":"00:09.705 ","End":"00:11.415","Text":"cannot tell without testing."},{"Start":"00:11.415 ","End":"00:14.775","Text":"Let\u0027s have a look at what acidity actually is."},{"Start":"00:14.775 ","End":"00:20.667","Text":"Actually we can see that our measurement for acidity are measured by numbers,"},{"Start":"00:20.667 ","End":"00:22.560","Text":"is what we call a pH."},{"Start":"00:22.560 ","End":"00:25.500","Text":"P stands for the decimal core algorithm of,"},{"Start":"00:25.500 ","End":"00:28.575","Text":"H is the hydrogen ion."},{"Start":"00:28.575 ","End":"00:34.380","Text":"So pH actually equals minus log to the base of"},{"Start":"00:34.380 ","End":"00:41.705","Text":"10 of the amount of hydrogen ions,"},{"Start":"00:41.705 ","End":"00:47.090","Text":"which mean that the more hydrogen ions we have because of their minus here,"},{"Start":"00:47.090 ","End":"00:49.805","Text":"the smaller our pH measurement will give us."},{"Start":"00:49.805 ","End":"00:57.920","Text":"Very strong acids have a very low pH with a very high amount of hydrogen ions"},{"Start":"00:57.920 ","End":"01:02.810","Text":"while basic solutions have a very high pH"},{"Start":"01:02.810 ","End":"01:08.790","Text":"and they have very little hydrogen ions when they have hydroxide ions."},{"Start":"01:10.880 ","End":"01:14.810","Text":"Now, when a base is added to a solution and we\u0027re talking about adding"},{"Start":"01:14.810 ","End":"01:18.320","Text":"a solution with very high pH,"},{"Start":"01:18.320 ","End":"01:20.030","Text":"what\u0027s going to happen,"},{"Start":"01:20.030 ","End":"01:23.989","Text":"the pH will of course increase."},{"Start":"01:23.989 ","End":"01:27.065","Text":"The rest of the answers are wrong."},{"Start":"01:27.065 ","End":"01:29.420","Text":"It will not decrease, it will not stay the same,"},{"Start":"01:29.420 ","End":"01:31.730","Text":"and we can tell without testing,"},{"Start":"01:31.730 ","End":"01:34.410","Text":"as we have just seen."}],"ID":24152},{"Watched":false,"Name":"Exercise 10","Duration":"25s","ChapterTopicVideoID":23265,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.525","Text":"1 carbon molecule can bind up to,"},{"Start":"00:03.525 ","End":"00:06.975","Text":"A, 1 other atom or molecule, B,"},{"Start":"00:06.975 ","End":"00:09.800","Text":"8 other atoms or molecules, C,"},{"Start":"00:09.800 ","End":"00:11.790","Text":"10 other atoms or molecules,"},{"Start":"00:11.790 ","End":"00:15.074","Text":"or D, 4 other atoms and molecules."},{"Start":"00:15.074 ","End":"00:19.530","Text":"Since carbon has 4 electrons in its outermost shell,"},{"Start":"00:19.530 ","End":"00:21.750","Text":"it can therefore, 4 bonds."},{"Start":"00:21.750 ","End":"00:25.210","Text":"The correct answer would be d, 4."}],"ID":24153},{"Watched":false,"Name":"Exercise 11","Duration":"47s","ChapterTopicVideoID":23266,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.875","Text":"Organic compounds."},{"Start":"00:01.875 ","End":"00:03.810","Text":"A. Always contain nitrogen."},{"Start":"00:03.810 ","End":"00:06.750","Text":"B. Are synthesized by only animal cells."},{"Start":"00:06.750 ","End":"00:09.150","Text":"C. Always contain carbon."},{"Start":"00:09.150 ","End":"00:12.360","Text":"Or D. Always contain oxygen."},{"Start":"00:12.360 ","End":"00:17.520","Text":"By definition, organic chemistry is the study of carbon compounds."},{"Start":"00:17.520 ","End":"00:22.230","Text":"Therefore, organic compounds will always contain carbon, of course."},{"Start":"00:22.230 ","End":"00:25.320","Text":"Some of them do contain nitrogen, but not necessarily."},{"Start":"00:25.320 ","End":"00:27.260","Text":"They are synthesized by animal cells,"},{"Start":"00:27.260 ","End":"00:29.210","Text":"but also by plant cells,"},{"Start":"00:29.210 ","End":"00:35.680","Text":"fungal cells, by bacteria, etc."},{"Start":"00:35.680 ","End":"00:37.665","Text":"Therefore B is wrong,"},{"Start":"00:37.665 ","End":"00:40.530","Text":"C, we said is correct,"},{"Start":"00:40.530 ","End":"00:43.220","Text":"and D, they can contain oxygen,"},{"Start":"00:43.220 ","End":"00:46.740","Text":"but not necessarily. We can mark C."}],"ID":24154},{"Watched":false,"Name":"Exercise 12","Duration":"49s","ChapterTopicVideoID":23267,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.695","Text":"What is the difference between ionic bonds and covalent bonds?"},{"Start":"00:04.695 ","End":"00:07.560","Text":"Ionic bonds are created between ions."},{"Start":"00:07.560 ","End":"00:09.735","Text":"While ions are charged atoms."},{"Start":"00:09.735 ","End":"00:14.985","Text":"If we have atoms that are charged negatively and positively close to each other,"},{"Start":"00:14.985 ","End":"00:16.995","Text":"they will form a bond between them"},{"Start":"00:16.995 ","End":"00:20.895","Text":"just as positively and negatively charged magnets will."},{"Start":"00:20.895 ","End":"00:24.675","Text":"In this case, the electrons are not shared between the atoms,"},{"Start":"00:24.675 ","End":"00:28.425","Text":"but rather they\u0027re associated more with 1 ion than the other."},{"Start":"00:28.425 ","End":"00:31.408","Text":"The ionic bonds are strong bonds,"},{"Start":"00:31.408 ","End":"00:32.720","Text":"but weaker than covalent bonds,"},{"Start":"00:32.720 ","End":"00:38.045","Text":"meaning it takes less energy to break an ionic bond compared to a strong covalent bond."},{"Start":"00:38.045 ","End":"00:42.035","Text":"In covalent bonds, the electrons are actually shared between the 2 atoms."},{"Start":"00:42.035 ","End":"00:44.810","Text":"That\u0027s why it\u0027s a lot harder to separate between them."},{"Start":"00:44.810 ","End":"00:49.050","Text":"That is the difference between ionic bonds and covalent bonds."}],"ID":24155},{"Watched":false,"Name":"Exercise 13","Duration":"1m 58s","ChapterTopicVideoID":23249,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.170 ","End":"00:04.080","Text":"How do buffers prevent pH changes?"},{"Start":"00:04.080 ","End":"00:07.290","Text":"Buffers absorb the free hydrogen ions and"},{"Start":"00:07.290 ","End":"00:10.695","Text":"hydroxide ions that result from chemical reactions."},{"Start":"00:10.695 ","End":"00:13.125","Text":"Because they can bond to these ions,"},{"Start":"00:13.125 ","End":"00:17.020","Text":"they prevent increases or decreases in pH."},{"Start":"00:17.330 ","End":"00:22.515","Text":"An example of a buffer system is the bicarbonate system in the human body."},{"Start":"00:22.515 ","End":"00:26.565","Text":"This system is able to absorb hydrogen and hydroxide ions,"},{"Start":"00:26.565 ","End":"00:31.830","Text":"preventing changes in pH and enabling cells to function properly."},{"Start":"00:31.830 ","End":"00:38.475","Text":"Acidic solution has a high concentration of hydrogen ions,"},{"Start":"00:38.475 ","End":"00:41.684","Text":"while a basic solution has low concentration"},{"Start":"00:41.684 ","End":"00:46.910","Text":"of hydrogen ions and a high concentration of hydroxide ions."},{"Start":"00:46.910 ","End":"00:52.565","Text":"Any buffer have to include a weak acid that can absorb"},{"Start":"00:52.565 ","End":"00:56.947","Text":"excess hydroxide ions and its conjugate base"},{"Start":"00:56.947 ","End":"01:01.865","Text":"which could absorb these excess hydrogen ions."},{"Start":"01:01.865 ","End":"01:07.085","Text":"The example of the bicarbonate system in the human body is given"},{"Start":"01:07.085 ","End":"01:14.610","Text":"by this weak acid,"},{"Start":"01:16.540 ","End":"01:23.880","Text":"which is constantly changing to this weak base."},{"Start":"01:31.730 ","End":"01:38.120","Text":"The base can absorb extra hydrogen ions,"},{"Start":"01:38.120 ","End":"01:45.130","Text":"and the acid is able to absorb extra hydroxide ions."},{"Start":"01:47.390 ","End":"01:52.080","Text":"In this way, changes in our blood are easily"},{"Start":"01:52.080 ","End":"01:58.060","Text":"absorbed and relatively our blood keeps a very constant pH."}],"ID":24137},{"Watched":false,"Name":"Exercise 14","Duration":"33s","ChapterTopicVideoID":23250,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.960","Text":"Why is carbon considered essential for organic life?"},{"Start":"00:03.960 ","End":"00:08.732","Text":"Since carbon is the basic building block of all organic molecules,"},{"Start":"00:08.732 ","End":"00:12.495","Text":"organic molecules essentially form cells and other structures,"},{"Start":"00:12.495 ","End":"00:15.930","Text":"where all biological processes of life are carried out."},{"Start":"00:15.930 ","End":"00:19.845","Text":"We have these basic structures based on carbon."},{"Start":"00:19.845 ","End":"00:23.820","Text":"Here it\u0027s the grayish black balls."},{"Start":"00:23.820 ","End":"00:26.715","Text":"The cell, which is the basic structure of life,"},{"Start":"00:26.715 ","End":"00:29.250","Text":"is made of these organic compounds."},{"Start":"00:29.250 ","End":"00:34.030","Text":"Therefore, carbon is considered essential for organic life."}],"ID":24138},{"Watched":false,"Name":"Exercise 15","Duration":"1m 51s","ChapterTopicVideoID":23251,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.130","Text":"Which of the following statements is false?"},{"Start":"00:02.130 ","End":"00:05.640","Text":"A; water is the universal solvent."},{"Start":"00:05.640 ","End":"00:09.525","Text":"Well, we do know that since water has its hydrogen bonds,"},{"Start":"00:09.525 ","End":"00:12.720","Text":"any polar molecules that will try to mix them will"},{"Start":"00:12.720 ","End":"00:16.830","Text":"easily be melted between the water molecules."},{"Start":"00:16.830 ","End":"00:19.920","Text":"Therefore, this statement is correct,"},{"Start":"00:19.920 ","End":"00:22.945","Text":"and since we\u0027re looking for the false statement,"},{"Start":"00:22.945 ","End":"00:25.615","Text":"we can X this one-off."},{"Start":"00:25.615 ","End":"00:30.550","Text":"B; water destabilizes temperature."},{"Start":"00:31.250 ","End":"00:35.585","Text":"Just take a look at this beautiful island here."},{"Start":"00:35.585 ","End":"00:37.400","Text":"If we look at the temperatures,"},{"Start":"00:37.400 ","End":"00:41.090","Text":"we know that on the island at night,"},{"Start":"00:41.090 ","End":"00:42.430","Text":"it will get cooler during the day,"},{"Start":"00:42.430 ","End":"00:43.670","Text":"it can get really hot."},{"Start":"00:43.670 ","End":"00:46.250","Text":"But the water\u0027s temperature is a lot more constant,"},{"Start":"00:46.250 ","End":"00:49.775","Text":"it changes a lot less, and this is again due to hydrogen bonds."},{"Start":"00:49.775 ","End":"00:53.390","Text":"Therefore, water stabilizes temperature,"},{"Start":"00:53.390 ","End":"00:55.745","Text":"and this statement is incorrect."},{"Start":"00:55.745 ","End":"00:58.055","Text":"Since we\u0027re looking for the false statement,"},{"Start":"00:58.055 ","End":"01:01.025","Text":"we can circle this answer."},{"Start":"01:01.025 ","End":"01:02.720","Text":"This is the correct answer."},{"Start":"01:02.720 ","End":"01:04.925","Text":"Let\u0027s have a look at the other statements."},{"Start":"01:04.925 ","End":"01:07.130","Text":"Water is essential for life."},{"Start":"01:07.130 ","End":"01:10.910","Text":"Well, yes, cells contain mostly water,"},{"Start":"01:10.910 ","End":"01:12.170","Text":"all living cells,"},{"Start":"01:12.170 ","End":"01:15.410","Text":"and therefore water is in fact essential for life."},{"Start":"01:15.410 ","End":"01:18.290","Text":"This is not false, it\u0027s the wrong answer."},{"Start":"01:18.290 ","End":"01:23.030","Text":"The water cohesive and adhesive properties are responsible for surface tension."},{"Start":"01:23.030 ","End":"01:29.105","Text":"Again, we\u0027re back to where the hydrogen bonds connect molecules of water,"},{"Start":"01:29.105 ","End":"01:32.750","Text":"and therefore water molecules are connected to one"},{"Start":"01:32.750 ","End":"01:36.625","Text":"another and create the surface tension."},{"Start":"01:36.625 ","End":"01:40.235","Text":"We know if we were not too heavy,"},{"Start":"01:40.235 ","End":"01:44.390","Text":"we could also walk on water like these bugs do."},{"Start":"01:44.390 ","End":"01:52.110","Text":"This statement is correct and therefore it is not false and we have our correct answer."}],"ID":24139},{"Watched":false,"Name":"Exercise 16","Duration":"2m 42s","ChapterTopicVideoID":23252,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.000","Text":"Which statement is false?"},{"Start":"00:03.000 ","End":"00:06.150","Text":"A, acids donate hydrogen ions,"},{"Start":"00:06.150 ","End":"00:09.240","Text":"bases donate hydroxide ions."},{"Start":"00:09.240 ","End":"00:14.005","Text":"B, both addition of bases and acids can change the pH of a solution."},{"Start":"00:14.005 ","End":"00:17.770","Text":"C, acids and bases will not neutralize each other,"},{"Start":"00:17.770 ","End":"00:21.205","Text":"and D, acids and bases can mix together."},{"Start":"00:21.205 ","End":"00:23.635","Text":"What is an acidic solution?"},{"Start":"00:23.635 ","End":"00:28.434","Text":"The acidity of the solution is measured by the pH,"},{"Start":"00:28.434 ","End":"00:34.690","Text":"which is actually a negative measurement to the number of hydrogen ions,"},{"Start":"00:34.690 ","End":"00:40.320","Text":"meaning that an acid has many high concentration of"},{"Start":"00:40.320 ","End":"00:45.950","Text":"hydrogen ions while basic solutions have a very low concentration of these ions,"},{"Start":"00:45.950 ","End":"00:50.130","Text":"a high concentration of hydroxide ions."},{"Start":"00:52.820 ","End":"00:55.470","Text":"Therefore, Statement A,"},{"Start":"00:55.470 ","End":"01:01.430","Text":"that acids donate hydrogen ions and bases donate hydroxide ions is true,"},{"Start":"01:01.430 ","End":"01:03.395","Text":"and since we\u0027re looking for the false statement,"},{"Start":"01:03.395 ","End":"01:05.645","Text":"we can cross this answer out."},{"Start":"01:05.645 ","End":"01:10.295","Text":"Statement B, both addition of bases and acids can change the pH of a solution."},{"Start":"01:10.295 ","End":"01:13.070","Text":"Of course, if we add to the solution an acid"},{"Start":"01:13.070 ","End":"01:17.630","Text":"containing a higher concentration of hydrogen ions,"},{"Start":"01:17.630 ","End":"01:20.870","Text":"we will change the pH of our solution,"},{"Start":"01:20.870 ","End":"01:22.730","Text":"making it more acid."},{"Start":"01:22.730 ","End":"01:27.000","Text":"The opposite can be said if we add bases"},{"Start":"01:27.000 ","End":"01:31.080","Text":"containing a high concentration of hydroxide ions,"},{"Start":"01:31.080 ","End":"01:34.070","Text":"therefore, this statement is true."},{"Start":"01:34.070 ","End":"01:36.140","Text":"Since we are looking for the false answer,"},{"Start":"01:36.140 ","End":"01:38.400","Text":"we can cross this answer out."},{"Start":"01:39.140 ","End":"01:43.565","Text":"Statement C, acids and bases will not neutralize each other."},{"Start":"01:43.565 ","End":"01:45.770","Text":"Well, in fact,"},{"Start":"01:45.770 ","End":"01:50.870","Text":"adding hydrogen ions and"},{"Start":"01:50.870 ","End":"01:58.155","Text":"hydroxide ions will lead to the formation of water molecules,"},{"Start":"01:58.155 ","End":"02:03.200","Text":"and therefore, if we have a strong base with a lot of"},{"Start":"02:03.200 ","End":"02:07.350","Text":"excess hydroxide ions and the more hydrogen ions"},{"Start":"02:07.350 ","End":"02:12.065","Text":"we\u0027d add it in by putting an acid would actually neutralize these hydroxide ions,"},{"Start":"02:12.065 ","End":"02:17.315","Text":"changing or neutralizing the strong base."},{"Start":"02:17.315 ","End":"02:24.070","Text":"Therefore, this statement is false and they will in fact neutralize each other."},{"Start":"02:24.070 ","End":"02:29.704","Text":"We can circle this answer to be at a correct answer as the false statement."},{"Start":"02:29.704 ","End":"02:31.220","Text":"Let\u0027s have a look at the last statement."},{"Start":"02:31.220 ","End":"02:33.305","Text":"Acids and bases can mix together."},{"Start":"02:33.305 ","End":"02:35.300","Text":"Of course, that is true. They can mix together."},{"Start":"02:35.300 ","End":"02:36.950","Text":"It is not a false statement,"},{"Start":"02:36.950 ","End":"02:41.310","Text":"and therefore it is the wrong answer to this question."}],"ID":24140},{"Watched":false,"Name":"Exercise 17","Duration":"3m 33s","ChapterTopicVideoID":23253,"CourseChapterTopicPlaylistID":108178,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.200 ","End":"00:04.650","Text":"A basic solution has a what level of pH"},{"Start":"00:04.650 ","End":"00:08.950","Text":"and can be neutralized by adding or removing what ion?"},{"Start":"00:08.950 ","End":"00:15.825","Text":"A. A basic solution has a low pH and can be neutralized by adding hydrogen ions."},{"Start":"00:15.825 ","End":"00:22.635","Text":"B. A basic solution has a high pH and can be neutralized by adding hydroxide ions."},{"Start":"00:22.635 ","End":"00:25.920","Text":"C. A basic solution has a low pH."},{"Start":"00:25.920 ","End":"00:29.400","Text":"It can be neutralized by removing hydrogen ions."},{"Start":"00:29.400 ","End":"00:32.925","Text":"D. A basic solution has a high pH."},{"Start":"00:32.925 ","End":"00:36.525","Text":"It can be neutralized by removing hydroxide ions."},{"Start":"00:36.525 ","End":"00:38.475","Text":"E. None of the above."},{"Start":"00:38.475 ","End":"00:42.650","Text":"Let\u0027s have a look at the pH scale or the acidity measurement scale."},{"Start":"00:42.650 ","End":"00:46.475","Text":"We measure the acidity by a measurement called pH."},{"Start":"00:46.475 ","End":"00:51.050","Text":"P stands for the decimal co-algorithm meaning actually"},{"Start":"00:51.050 ","End":"00:58.925","Text":"minus log base 10 of the H,"},{"Start":"00:58.925 ","End":"01:04.055","Text":"that\u0027s the amount of hydrogen ions in the solution."},{"Start":"01:04.055 ","End":"01:09.275","Text":"What this actually means is that the more hydrogen ions we have in the solution,"},{"Start":"01:09.275 ","End":"01:15.380","Text":"the higher this whole number will be and since we have a minus over here,"},{"Start":"01:15.380 ","End":"01:17.705","Text":"the pH will actually be negative."},{"Start":"01:17.705 ","End":"01:20.630","Text":"The more hydrogen ions we have in the solution,"},{"Start":"01:20.630 ","End":"01:23.975","Text":"the more acidic it is and the lower the pH will be."},{"Start":"01:23.975 ","End":"01:29.220","Text":"Acid is defined as a solution with a high concentration of hydrogen ions."},{"Start":"01:30.100 ","End":"01:34.805","Text":"The opposite is right for a basic or an alkali solution."},{"Start":"01:34.805 ","End":"01:40.505","Text":"Here we have a small amount of hydrogen ions and our pH gets to be a lot bigger."},{"Start":"01:40.505 ","End":"01:45.890","Text":"Here we have a high number of pH and we have a very small number of hydrogen ions,"},{"Start":"01:45.890 ","End":"01:50.700","Text":"on the contrary, we have a high number of hydroxide ions."},{"Start":"01:51.460 ","End":"01:55.970","Text":"What would happen if hydroxide ions met hydrogen ions?"},{"Start":"01:55.970 ","End":"02:01.100","Text":"See we have here the H and we have here OH minus"},{"Start":"02:01.100 ","End":"02:07.350","Text":"and when they are added together what we get is water."},{"Start":"02:07.350 ","End":"02:09.905","Text":"Therefore, the first part of the question,"},{"Start":"02:09.905 ","End":"02:13.475","Text":"telling us that the basic solution has what kind of pH?"},{"Start":"02:13.475 ","End":"02:16.715","Text":"We now know that basic solutions have a high pH."},{"Start":"02:16.715 ","End":"02:21.575","Text":"Therefore, we can cross out any answer telling us that basic solution has low pH"},{"Start":"02:21.575 ","End":"02:28.400","Text":"and know that these answers are already on the right path."},{"Start":"02:28.400 ","End":"02:31.580","Text":"Now let\u0027s have a look at the second part of the question."},{"Start":"02:31.580 ","End":"02:37.770","Text":"We want to neutralize the basic solution by adding or removing ions."},{"Start":"02:37.850 ","End":"02:45.940","Text":"Adding 1 hydroxide ion to the solution will give us an even more basic solution."},{"Start":"02:45.940 ","End":"02:52.550","Text":"On the contrary, removing these will give us a less basic solution."},{"Start":"02:52.550 ","End":"02:54.965","Text":"How can these hydroxide ions be removed?"},{"Start":"02:54.965 ","End":"03:00.420","Text":"One of the easier ways to remove them is to add hydrogen ions to the solution which in"},{"Start":"03:00.420 ","End":"03:08.045","Text":"turn give us water molecules here by neutralizing the hydroxide ions."},{"Start":"03:08.045 ","End":"03:11.060","Text":"If we wanted to neutralize this basic solution,"},{"Start":"03:11.060 ","End":"03:20.160","Text":"you could either remove the hydroxide ions or add hydrogen ions."},{"Start":"03:20.170 ","End":"03:23.010","Text":"In A, we have part of the answer wrong."},{"Start":"03:23.010 ","End":"03:24.450","Text":"In B, part of the answer is wrong."},{"Start":"03:24.450 ","End":"03:25.950","Text":"In C, everything is wrong."},{"Start":"03:25.950 ","End":"03:27.435","Text":"In D, everything is right."},{"Start":"03:27.435 ","End":"03:30.125","Text":"In E, none of the above, it doesn\u0027t work at all."},{"Start":"03:30.125 ","End":"03:34.320","Text":"We can now highlight the right answer and we are done."}],"ID":24141}],"Thumbnail":null,"ID":108178},{"Name":"Biological Macromolecules","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Introduction","Duration":"4m 29s","ChapterTopicVideoID":23286,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":"https://www.proprep.uk/Images/Videos_Thumbnails/23286.jpeg","UploadDate":"2020-12-01T07:20:06.4000000","DurationForVideoObject":"PT4M29S","Description":null,"MetaTitle":"Biological Macromolecules- Introduction: Video + Workbook | Proprep","MetaDescription":"Introduction to Biology - Biological Macromolecules. Watch the video made by an expert in the field. Download the workbook and maximize your learning.","Canonical":"https://www.proprep.uk/general-modules/all/introduction-to-biology/introduction-to-biology/biological-macromolecules/vid24125","VideoComments":[],"Subtitles":[{"Start":"00:00.200 ","End":"00:05.340","Text":"Hi, today we\u0027re going to introduce biological macromolecules."},{"Start":"00:05.340 ","End":"00:07.155","Text":"By the end of this section,"},{"Start":"00:07.155 ","End":"00:10.020","Text":"you\u0027ll be able to understand the synthesis of"},{"Start":"00:10.020 ","End":"00:14.250","Text":"macromolecules and explain the hydration or as other name,"},{"Start":"00:14.250 ","End":"00:18.105","Text":"condensation and hydrolysis reactions."},{"Start":"00:18.105 ","End":"00:20.940","Text":"What are macromolecules?"},{"Start":"00:20.940 ","End":"00:24.965","Text":"These are larger organic molecules that are necessary for life."},{"Start":"00:24.965 ","End":"00:26.929","Text":"They are also known as polymers,"},{"Start":"00:26.929 ","End":"00:31.864","Text":"meaning many parts because they\u0027re made out of single units,"},{"Start":"00:31.864 ","End":"00:35.075","Text":"known as monomers, which means single parts."},{"Start":"00:35.075 ","End":"00:40.745","Text":"The polymer is more than the sum of its parts and acquires new characteristics."},{"Start":"00:40.745 ","End":"00:43.010","Text":"For example, the asthmatic pressure of"},{"Start":"00:43.010 ","End":"00:46.280","Text":"a polymer is much lower than that foreign by its ingredients."},{"Start":"00:46.280 ","End":"00:51.295","Text":"This is an important advantage in the maintenance of cellular asthmatic conditions."},{"Start":"00:51.295 ","End":"00:57.680","Text":"The 4 major classes of biological macromolecules are carbohydrates,"},{"Start":"00:57.680 ","End":"01:01.715","Text":"including sugars, starches, fibers and more."},{"Start":"01:01.715 ","End":"01:04.280","Text":"Lipids, including oils,"},{"Start":"01:04.280 ","End":"01:08.630","Text":"fats, waxes, other substances."},{"Start":"01:08.630 ","End":"01:12.230","Text":"Proteins that perform a large array of tasks."},{"Start":"01:12.230 ","End":"01:14.630","Text":"Among them, building cellular structures,"},{"Start":"01:14.630 ","End":"01:18.545","Text":"enzymes, hormones, many more functions."},{"Start":"01:18.545 ","End":"01:23.255","Text":"Last but not least, are the nucleic acids, DNA and RNA."},{"Start":"01:23.255 ","End":"01:25.950","Text":"These encode a genetic data."},{"Start":"01:26.110 ","End":"01:29.135","Text":"How are macromolecules formed?"},{"Start":"01:29.135 ","End":"01:31.549","Text":"They are formed by condensation reactions."},{"Start":"01:31.549 ","End":"01:34.640","Text":"This is when a monomer, a single unit,"},{"Start":"01:34.640 ","End":"01:38.525","Text":"joins with another monomer with the release of a water molecule."},{"Start":"01:38.525 ","End":"01:42.185","Text":"This leads to the formation of a covalent bond."},{"Start":"01:42.185 ","End":"01:48.349","Text":"These types of reactions are known as dehydration or condensation reactions."},{"Start":"01:48.349 ","End":"01:50.705","Text":"That\u0027s because we\u0027ll soon see why it is."},{"Start":"01:50.705 ","End":"01:52.940","Text":"Let\u0027s look at this schematic image,"},{"Start":"01:52.940 ","End":"01:54.334","Text":"here we have our monomers."},{"Start":"01:54.334 ","End":"01:56.960","Text":"This monomer has hydrogen atom."},{"Start":"01:56.960 ","End":"02:00.095","Text":"This monomer has a hydrogen and an oxygen atom,"},{"Start":"02:00.095 ","End":"02:04.875","Text":"which are joined to form water molecule."},{"Start":"02:04.875 ","End":"02:09.440","Text":"The monomers are now connected by a covalent bond."},{"Start":"02:09.440 ","End":"02:12.800","Text":"Effectively, they have been dehydrated,"},{"Start":"02:12.800 ","End":"02:16.925","Text":"water has been taken out of them, hence dehydration."},{"Start":"02:16.925 ","End":"02:23.630","Text":"Water was condensed and formed while these monomers connect to each other."},{"Start":"02:23.630 ","End":"02:26.440","Text":"It\u0027s also called condensation reactions."},{"Start":"02:26.440 ","End":"02:30.229","Text":"How are these macromolecules separated or digested?"},{"Start":"02:30.229 ","End":"02:33.425","Text":"The answer is by hydrolysis reactions."},{"Start":"02:33.425 ","End":"02:38.240","Text":"This is when polymers are broken down into smaller units, the monomers."},{"Start":"02:38.240 ","End":"02:43.805","Text":"A molecule of water is used for each bond broken by these reactions."},{"Start":"02:43.805 ","End":"02:48.065","Text":"These reactions are known as hydrolysis reactions, and we\u0027ll see why."},{"Start":"02:48.065 ","End":"02:51.650","Text":"We\u0027ll see here, we have here a polymer made of,"},{"Start":"02:51.650 ","End":"02:53.915","Text":"in this example of 3 monomers."},{"Start":"02:53.915 ","End":"02:59.255","Text":"We have our water molecule which is added between these 2 monomers."},{"Start":"02:59.255 ","End":"03:01.070","Text":"The water is being taken apart,"},{"Start":"03:01.070 ","End":"03:05.045","Text":"donates 1 hydrogen atom to this monomer,"},{"Start":"03:05.045 ","End":"03:08.615","Text":"and hydrogen and an oxygen to this monomer,"},{"Start":"03:08.615 ","End":"03:13.850","Text":"effectively taking apart that covalent bond and separating them into 2 monomers."},{"Start":"03:13.850 ","End":"03:16.910","Text":"These are hydrolysis reactions."},{"Start":"03:16.910 ","End":"03:20.150","Text":"Dehydration and hydrolysis reactions are"},{"Start":"03:20.150 ","End":"03:23.900","Text":"similar for all the classes of macromolecules that we introduced before."},{"Start":"03:23.900 ","End":"03:28.415","Text":"But each of the monomers and polymers reaction is specific to its own class, of course."},{"Start":"03:28.415 ","End":"03:30.770","Text":"If you want to look at the example from the carbohydrates,"},{"Start":"03:30.770 ","End":"03:36.470","Text":"we have here monomers of sugar which are joined together in a covalent bond."},{"Start":"03:36.470 ","End":"03:42.635","Text":"Each of these monomers donates its own part to condense a single molecule of water."},{"Start":"03:42.635 ","End":"03:47.107","Text":"While the opposite, the hydrolysis of polymer,"},{"Start":"03:47.107 ","End":"03:52.460","Text":"we have here an example of 2 sugar molecules bonded covalently."},{"Start":"03:52.460 ","End":"03:56.255","Text":"Here we have our molecule of water,"},{"Start":"03:56.255 ","End":"04:00.140","Text":"which is about to be taken apart, hydrolysis."},{"Start":"04:00.140 ","End":"04:05.030","Text":"Here\u0027s the water molecule and our 2 separated monomers."},{"Start":"04:05.030 ","End":"04:08.420","Text":"Typically, the hydration reactions require"},{"Start":"04:08.420 ","End":"04:12.485","Text":"an investment of energy because they form a new covalent bond."},{"Start":"04:12.485 ","End":"04:14.180","Text":"While the hydrolysis reactions,"},{"Start":"04:14.180 ","End":"04:15.485","Text":"like we can see here,"},{"Start":"04:15.485 ","End":"04:19.310","Text":"typically release energy by breaking the bonds."},{"Start":"04:19.310 ","End":"04:23.660","Text":"We now understand the synthesis of macromolecules and we can explain"},{"Start":"04:23.660 ","End":"04:28.409","Text":"dehydration or condensation and hydrolysis reactions."}],"ID":24125},{"Watched":false,"Name":"Proteins","Duration":"6m 25s","ChapterTopicVideoID":23289,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.010 ","End":"00:05.130","Text":"Hi, we\u0027re learning about biological macromolecules."},{"Start":"00:05.130 ","End":"00:07.500","Text":"Today we\u0027ll speak about proteins."},{"Start":"00:07.500 ","End":"00:09.315","Text":"By the end of this section,"},{"Start":"00:09.315 ","End":"00:14.370","Text":"you\u0027ll be able to describe the functions proteins perform in the cell and in tissues."},{"Start":"00:14.370 ","End":"00:18.465","Text":"Discuss the relationship between amino acids and protein."},{"Start":"00:18.465 ","End":"00:21.855","Text":"Explain the 4 levels of protein organization,"},{"Start":"00:21.855 ","End":"00:26.145","Text":"and describe the ways in which protein shape and function are linked."},{"Start":"00:26.145 ","End":"00:28.919","Text":"What are proteins?"},{"Start":"00:28.919 ","End":"00:32.085","Text":"Proteins are a class of macromolecules that"},{"Start":"00:32.085 ","End":"00:35.570","Text":"perform diverse range of functions for the cell."},{"Start":"00:35.570 ","End":"00:40.240","Text":"Proteins perform most of the tasks the body needs to function."},{"Start":"00:40.240 ","End":"00:44.570","Text":"They\u0027re the most elaborate of life\u0027s molecules."},{"Start":"00:44.570 ","End":"00:47.285","Text":"Proteins have many functions."},{"Start":"00:47.285 ","End":"00:52.415","Text":"These include enzymes which speed up the rate of chemical reactions."},{"Start":"00:52.415 ","End":"00:54.955","Text":"For example, pepsin in our stomachs"},{"Start":"00:54.955 ","End":"00:58.295","Text":"breaks down the proteins to their basic building blocks."},{"Start":"00:58.295 ","End":"01:00.530","Text":"Transport proteins such as"},{"Start":"01:00.530 ","End":"01:04.475","Text":"hemoglobin carries substances in the blood throughout the body."},{"Start":"01:04.475 ","End":"01:08.810","Text":"Structural proteins build membranes in other structures."},{"Start":"01:08.810 ","End":"01:14.435","Text":"The actin and myosin they build the muscle fiber are good example for these proteins."},{"Start":"01:14.435 ","End":"01:19.400","Text":"Antibodies in our immune system protect the body from pathogens."},{"Start":"01:19.400 ","End":"01:22.610","Text":"Storage materials like the clear albumin in"},{"Start":"01:22.610 ","End":"01:26.600","Text":"the egg white provide nourishment to the developing fetus in the egg."},{"Start":"01:26.600 ","End":"01:30.710","Text":"Hormones coordinate the activity of different body systems,"},{"Start":"01:30.710 ","End":"01:34.880","Text":"like the insulin that regulates blood glucose levels."},{"Start":"01:34.880 ","End":"01:39.230","Text":"The protein structure is organized under 4 levels;"},{"Start":"01:39.230 ","End":"01:44.989","Text":"primary, secondary, tertiary, and quaternary."},{"Start":"01:44.989 ","End":"01:49.760","Text":"The primary structure is the unique sequence of amino acids."},{"Start":"01:49.760 ","End":"01:54.409","Text":"Amino acids are the building blocks or the monomers of proteins."},{"Start":"01:54.409 ","End":"01:59.945","Text":"Here we see that each amino acid is abbreviated by 3 letters."},{"Start":"01:59.945 ","End":"02:04.040","Text":"Each amino acid has a central carbon,"},{"Start":"02:04.040 ","End":"02:07.030","Text":"that is linked to an amino group,"},{"Start":"02:07.030 ","End":"02:09.315","Text":"to a carboxyl group,"},{"Start":"02:09.315 ","End":"02:11.115","Text":"to a hydrogen atom,"},{"Start":"02:11.115 ","End":"02:13.160","Text":"and also to an R group,"},{"Start":"02:13.160 ","End":"02:15.720","Text":"also called side chain."},{"Start":"02:15.880 ","End":"02:19.625","Text":"There are 20 commonly occurring amino acids,"},{"Start":"02:19.625 ","End":"02:22.865","Text":"each of which differs in the R group."},{"Start":"02:22.865 ","End":"02:27.350","Text":"This group determines the chemical nature of the amino acid."},{"Start":"02:27.350 ","End":"02:32.285","Text":"Each amino acid is linked to its neighbors by a peptide bond."},{"Start":"02:32.285 ","End":"02:37.085","Text":"Peptide bond formation is a dehydration synthesis reaction."},{"Start":"02:37.085 ","End":"02:39.890","Text":"The carboxyl group of 1 amino acid"},{"Start":"02:39.890 ","End":"02:45.210","Text":"here is linked to the amino group of the incoming amino acid."},{"Start":"02:46.240 ","End":"02:50.185","Text":"In the process, a molecule of water is released."},{"Start":"02:50.185 ","End":"02:53.480","Text":"We can see here the oxygen and the 2 hydrogens,"},{"Start":"02:53.480 ","End":"02:55.490","Text":"that eventually form this water."},{"Start":"02:55.490 ","End":"02:58.685","Text":"The R groups which represent the amino acids,"},{"Start":"02:58.685 ","End":"03:03.210","Text":"eventually create a long chain known as a polypeptide."},{"Start":"03:03.490 ","End":"03:08.060","Text":"Here we have a polypeptide made of many amino acids."},{"Start":"03:08.060 ","End":"03:12.470","Text":"The cells link the amino acids together to form these polypeptides."},{"Start":"03:12.470 ","End":"03:15.245","Text":"The arrangement of the amino acids makes"},{"Start":"03:15.245 ","End":"03:18.950","Text":"each protein different and unique in structure and in function."},{"Start":"03:18.950 ","End":"03:25.520","Text":"A slight change in primary structure of a protein affects its ability to function."},{"Start":"03:25.520 ","End":"03:29.150","Text":"This leads us to the secondary level of structure."},{"Start":"03:29.150 ","End":"03:32.210","Text":"The local folding of the polypeptide to form"},{"Start":"03:32.210 ","End":"03:35.950","Text":"structures constitutes the secondary structure."},{"Start":"03:35.950 ","End":"03:41.400","Text":"Certain amino acids have a propensity to form an Alpha-helix,"},{"Start":"03:41.680 ","End":"03:46.890","Text":"while others have a propensity to form a Beta-pleated sheet."},{"Start":"03:48.520 ","End":"03:52.580","Text":"These structures form because of hydrogen bonding between"},{"Start":"03:52.580 ","End":"03:56.630","Text":"carbonyl and amino groups in the peptide backbone."},{"Start":"03:56.630 ","End":"04:02.165","Text":"The overall 3-dimensional structure is a tertiary structure."},{"Start":"04:02.165 ","End":"04:07.865","Text":"The tertiary structure of proteins is determined by a variety of chemical interactions."},{"Start":"04:07.865 ","End":"04:11.645","Text":"These include; hydrophobic interactions,"},{"Start":"04:11.645 ","End":"04:21.480","Text":"ionic bonding, hydrogen bonding, and disulfide linkages."},{"Start":"04:21.480 ","End":"04:24.810","Text":"In this way with the Alpha-helixes and"},{"Start":"04:24.810 ","End":"04:28.640","Text":"the Beta-pleated sheets all connecting to each other in certain ways,"},{"Start":"04:28.640 ","End":"04:32.900","Text":"we got our overall 3-dimensional structure, the tertiary structure."},{"Start":"04:32.900 ","End":"04:35.925","Text":"In many cases the proteins stay this way,"},{"Start":"04:35.925 ","End":"04:37.420","Text":"but in some cases,"},{"Start":"04:37.420 ","End":"04:42.200","Text":"they group together with other polypeptides to form the quaternary structure."},{"Start":"04:42.200 ","End":"04:47.830","Text":"This is when 2 or more polypeptides combine to form the complete protein structure."},{"Start":"04:47.830 ","End":"04:51.860","Text":"The configuration is known as the quaternary structure of a protein."},{"Start":"04:51.860 ","End":"04:54.830","Text":"To summarize things up,"},{"Start":"04:54.830 ","End":"04:57.110","Text":"a protein structure has 4 levels;"},{"Start":"04:57.110 ","End":"05:01.915","Text":"primary, secondary, tertiary, and quaternary."},{"Start":"05:01.915 ","End":"05:06.785","Text":"The primary structure is the unique sequence of the amino acids."},{"Start":"05:06.785 ","End":"05:09.710","Text":"The secondary structure are"},{"Start":"05:09.710 ","End":"05:14.780","Text":"the Alpha-helixes and the Beta-pleated sheets that these amino acids form."},{"Start":"05:14.780 ","End":"05:19.850","Text":"A tertiary structure is the way that these structures connect with each other,"},{"Start":"05:19.850 ","End":"05:22.320","Text":"and when we add a few polypeptides like this,"},{"Start":"05:22.320 ","End":"05:26.555","Text":"they can connect to form a quaternary structure of a protein."},{"Start":"05:26.555 ","End":"05:30.500","Text":"Protein shape and function are intricately linked."},{"Start":"05:30.500 ","End":"05:33.500","Text":"Any change in shape caused by changes in temperature,"},{"Start":"05:33.500 ","End":"05:40.660","Text":"such as this egg or pH may lead to protein denaturation and loss in function."},{"Start":"05:40.660 ","End":"05:43.490","Text":"It was originally thought that the proteins"},{"Start":"05:43.490 ","End":"05:46.534","Text":"themselves are responsible for the folding process."},{"Start":"05:46.534 ","End":"05:50.150","Text":"Only recently was it found that often they receive assistance in"},{"Start":"05:50.150 ","End":"05:53.824","Text":"the folding process from protein helpers known as chaperones."},{"Start":"05:53.824 ","End":"05:57.954","Text":"These associate with the target protein during the folding process,"},{"Start":"05:57.954 ","End":"06:00.110","Text":"they act by preventing aggregation of"},{"Start":"06:00.110 ","End":"06:03.170","Text":"polypeptides that make up the complete protein structure,"},{"Start":"06:03.170 ","End":"06:09.245","Text":"and they dissociate from the protein once a target protein is folded."},{"Start":"06:09.245 ","End":"06:13.880","Text":"We\u0027ve described the functions of proteins perform in a cell and in tissues."},{"Start":"06:13.880 ","End":"06:17.660","Text":"We discussed the relationship between amino acids and proteins."},{"Start":"06:17.660 ","End":"06:21.080","Text":"We explained the 4 different levels of protein organization,"},{"Start":"06:21.080 ","End":"06:25.530","Text":"and we described the ways in which protein shape and function are linked."}],"ID":24128},{"Watched":false,"Name":"Lipids Part 1","Duration":"9m 58s","ChapterTopicVideoID":23287,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.490 ","End":"00:05.835","Text":"Hi. We\u0027re studying biological macromolecules."},{"Start":"00:05.835 ","End":"00:09.135","Text":"Today is the first section about lipids."},{"Start":"00:09.135 ","End":"00:11.145","Text":"By the end of this section,"},{"Start":"00:11.145 ","End":"00:14.205","Text":"you\u0027ll be able to explain the different roles of lipids,"},{"Start":"00:14.205 ","End":"00:17.220","Text":"described the 4 major types of lipids,"},{"Start":"00:17.220 ","End":"00:21.225","Text":"differentiate between saturated and unsaturated fatty acids,"},{"Start":"00:21.225 ","End":"00:25.060","Text":"and define cis and trans fats."},{"Start":"00:25.430 ","End":"00:31.395","Text":"By definition, lipids are a diverse group of large organic molecules,"},{"Start":"00:31.395 ","End":"00:33.315","Text":"typically made of hydrocarbons."},{"Start":"00:33.315 ","End":"00:36.855","Text":"These molecules are soluble in non-polar solvents."},{"Start":"00:36.855 ","End":"00:41.730","Text":"Hydrocarbons are molecules consisting"},{"Start":"00:41.730 ","End":"00:49.300","Text":"only carbons and hydrogen."},{"Start":"00:56.950 ","End":"00:59.345","Text":"Being such a diverse group,"},{"Start":"00:59.345 ","End":"01:02.990","Text":"the characteristics of lipids that unite them are that"},{"Start":"01:02.990 ","End":"01:06.710","Text":"lipids are non-polar and therefore they\u0027re hydrophobic,"},{"Start":"01:06.710 ","End":"01:08.720","Text":"meaning that they\u0027re not soluble in water."},{"Start":"01:08.720 ","End":"01:11.030","Text":"You can see this cup of water here with oil"},{"Start":"01:11.030 ","End":"01:14.200","Text":"dripping in it and the oil does not mix in the water."},{"Start":"01:14.200 ","End":"01:19.700","Text":"Lipids are soluble in hydrophobic solvents and oils would mix in other oils,"},{"Start":"01:19.700 ","End":"01:23.080","Text":"for example, or in other hydrophobic solvents,"},{"Start":"01:23.080 ","End":"01:31.160","Text":"mainly being hydrocarbons that are also non-polar,"},{"Start":"01:31.160 ","End":"01:36.390","Text":"and they will mix well with oils."},{"Start":"01:37.670 ","End":"01:42.275","Text":"For example, lipids are major component of cell membranes."},{"Start":"01:42.275 ","End":"01:43.505","Text":"We\u0027ll take a look at this cell."},{"Start":"01:43.505 ","End":"01:46.295","Text":"We\u0027ll see that, here this is the inside, this is the outside,"},{"Start":"01:46.295 ","End":"01:49.280","Text":"and the membrane is actually made of"},{"Start":"01:49.280 ","End":"01:53.540","Text":"a double layer of these phospholipids that we\u0027ll talk about later on today."},{"Start":"01:53.540 ","End":"01:56.375","Text":"Lipids also function as chemical messengers."},{"Start":"01:56.375 ","End":"01:57.950","Text":"Many of the hormones, for example,"},{"Start":"01:57.950 ","End":"01:59.876","Text":"testosterone or others,"},{"Start":"01:59.876 ","End":"02:06.460","Text":"which dictate the physiological gender of an animal, are actually lipids."},{"Start":"02:06.460 ","End":"02:09.240","Text":"Lipids are also used as waterproofing."},{"Start":"02:09.240 ","End":"02:12.830","Text":"If we take a look, we can see here these droplets of water on the feathers."},{"Start":"02:12.830 ","End":"02:16.235","Text":"They\u0027re not soaking the feathers and they\u0027re certainly not soaking the duck."},{"Start":"02:16.235 ","End":"02:20.600","Text":"If you take a look, you\u0027ll see here that the water just rolls off the feathers."},{"Start":"02:20.600 ","End":"02:24.290","Text":"That\u0027s because the ducks have a special gland with fat, which is lipids."},{"Start":"02:24.290 ","End":"02:27.875","Text":"They use it to spread it all over their feathers,"},{"Start":"02:27.875 ","End":"02:30.380","Text":"turning the feathers to be hydrophobic."},{"Start":"02:30.380 ","End":"02:33.350","Text":"1 of the main functions of lipids is that they\u0027re used as"},{"Start":"02:33.350 ","End":"02:36.485","Text":"long-term energy storage because chemically,"},{"Start":"02:36.485 ","End":"02:39.890","Text":"they are very efficient and carry a lot of energy."},{"Start":"02:39.890 ","End":"02:42.860","Text":"Animals store extra energy as fat."},{"Start":"02:42.860 ","End":"02:45.860","Text":"Plants also store this energy as fat."},{"Start":"02:45.860 ","End":"02:48.380","Text":"These cashews are very rich in oil,"},{"Start":"02:48.380 ","End":"02:50.570","Text":"which is actually meant to give"},{"Start":"02:50.570 ","End":"02:56.435","Text":"the embryo inside the seed a lot of energy when it begins to grow."},{"Start":"02:56.435 ","End":"02:59.420","Text":"Lipids are also used for heat insulation."},{"Start":"02:59.420 ","End":"03:04.940","Text":"This Harp Seal can live in a freezing ice field and dive in the icy waters and still stay"},{"Start":"03:04.940 ","End":"03:11.060","Text":"warm because it\u0027s insulated with a very thick layer of fat on the inside of its skin."},{"Start":"03:11.060 ","End":"03:14.780","Text":"Lipids are also used for cushioning against physical shock."},{"Start":"03:14.780 ","End":"03:18.170","Text":"1 example would be the thin layer of fat that"},{"Start":"03:18.170 ","End":"03:21.610","Text":"we have around our eyeballs and therefore even when we jump and run,"},{"Start":"03:21.610 ","End":"03:25.620","Text":"or even hit our head, our eyes are cushioned from the shock."},{"Start":"03:25.760 ","End":"03:29.780","Text":"The 4 types of lipids are fats and oils,"},{"Start":"03:29.780 ","End":"03:34.145","Text":"waxes, steroids, and phospholipids."},{"Start":"03:34.145 ","End":"03:39.335","Text":"We\u0027ll now proceed to discuss fats and oils."},{"Start":"03:39.335 ","End":"03:44.360","Text":"Chemically speaking, fats and oils are a very efficient way to store energy."},{"Start":"03:44.360 ","End":"03:51.200","Text":"Dietary fat consists largely of the molecule triglyceride. This molecule here."},{"Start":"03:51.200 ","End":"03:56.300","Text":"It\u0027s a combination of glycerol with 3 fatty acid chains."},{"Start":"03:56.300 ","End":"03:58.730","Text":"The glycerol is this part,"},{"Start":"03:58.730 ","End":"04:05.100","Text":"and the 3 fatty acid chains are these 1, 2 and 3."},{"Start":"04:05.100 ","End":"04:07.380","Text":"In this example, we see that 1 of them looks"},{"Start":"04:07.380 ","End":"04:11.290","Text":"straight and the other 2 seem to have these angles."},{"Start":"04:11.290 ","End":"04:14.870","Text":"The difference between these fatty acid chains is"},{"Start":"04:14.870 ","End":"04:18.335","Text":"that the bottom 1 is saturated with hydrogen atoms,"},{"Start":"04:18.335 ","End":"04:23.840","Text":"therefore, there are double bonds between the carbon atoms making these angles appear."},{"Start":"04:23.840 ","End":"04:29.945","Text":"Chains that are saturated with hydrogen atoms obtain a straight confirmation."},{"Start":"04:29.945 ","End":"04:35.555","Text":"Like in this stearic acid, we see that each and every 1 of the carbon atoms has"},{"Start":"04:35.555 ","End":"04:41.990","Text":"2 hydrogen atoms with covalent bonds on both sides."},{"Start":"04:41.990 ","End":"04:47.075","Text":"Therefore, the covalent bonds between the carbon atoms are all single."},{"Start":"04:47.075 ","End":"04:52.525","Text":"What we get is a very straight chain of carbon atoms."},{"Start":"04:52.525 ","End":"04:57.105","Text":"On the other hand, in unsaturated chains, there\u0027s this break."},{"Start":"04:57.105 ","End":"04:59.715","Text":"Here we have cis oleic acid."},{"Start":"04:59.715 ","End":"05:06.140","Text":"We see that these 2 carbon atoms only have 1 covalent bond with hydrogen atoms."},{"Start":"05:06.140 ","End":"05:09.080","Text":"Therefore, they make a double bond between themselves."},{"Start":"05:09.080 ","End":"05:12.230","Text":"This double bond is what holds the angle between"},{"Start":"05:12.230 ","End":"05:16.175","Text":"the 2 carbon atoms and gives the whole chain an angle."},{"Start":"05:16.175 ","End":"05:21.290","Text":"Thus, saturated fats are more easily densely packed and"},{"Start":"05:21.290 ","End":"05:26.300","Text":"conform to a solid state at much lower temperatures. How is this?"},{"Start":"05:26.300 ","End":"05:28.565","Text":"If we would take matches,"},{"Start":"05:28.565 ","End":"05:30.271","Text":"we\u0027d have straight matches,"},{"Start":"05:30.271 ","End":"05:32.615","Text":"and these matches that are broken into angles,"},{"Start":"05:32.615 ","End":"05:35.315","Text":"and we\u0027d like to pack them into our matchbox."},{"Start":"05:35.315 ","End":"05:38.600","Text":"Which group would more easily and densely pack?"},{"Start":"05:38.600 ","End":"05:41.600","Text":"Obviously, the answer is the straight matches."},{"Start":"05:41.600 ","End":"05:43.790","Text":"You see how easily they fit inside."},{"Start":"05:43.790 ","End":"05:48.935","Text":"The same thing happens when we want to pack these long fatty acid chains."},{"Start":"05:48.935 ","End":"05:52.880","Text":"If we want to pack saturated fats,"},{"Start":"05:52.880 ","End":"05:55.520","Text":"saturated fats are like the straight matches,"},{"Start":"05:55.520 ","End":"05:56.716","Text":"they fit very easily."},{"Start":"05:56.716 ","End":"05:59.390","Text":"Therefore, a lard, butter and cream contain"},{"Start":"05:59.390 ","End":"06:04.470","Text":"saturated fats are solid at room temperature."},{"Start":"06:05.870 ","End":"06:08.915","Text":"Lard, butter and cream,"},{"Start":"06:08.915 ","End":"06:12.065","Text":"the saturated fats are these ones."},{"Start":"06:12.065 ","End":"06:14.345","Text":"These are the fatty acid chains."},{"Start":"06:14.345 ","End":"06:16.280","Text":"If we would choose between the matches,"},{"Start":"06:16.280 ","End":"06:18.985","Text":"we would say that these are the straight ones."},{"Start":"06:18.985 ","End":"06:25.100","Text":"On the other hand, oils that are extracted from plants contain unsaturated fats."},{"Start":"06:25.100 ","End":"06:27.740","Text":"These fats are unsaturated,"},{"Start":"06:27.740 ","End":"06:29.540","Text":"and therefore they have the angle."},{"Start":"06:29.540 ","End":"06:30.830","Text":"Since they have the angle,"},{"Start":"06:30.830 ","End":"06:33.920","Text":"they\u0027re less densely packed and you\u0027re going to have to"},{"Start":"06:33.920 ","End":"06:38.360","Text":"freeze the oil in order to get the oil to conform to a solid state."},{"Start":"06:38.360 ","End":"06:41.780","Text":"Again, we would choose and say that"},{"Start":"06:41.780 ","End":"06:45.379","Text":"these unsaturated fats aren\u0027t like the broken matches,"},{"Start":"06:45.379 ","End":"06:48.030","Text":"which don\u0027t pack very well."},{"Start":"06:48.890 ","End":"06:54.185","Text":"We know that oils that are extracted from plants contain unsaturated fats."},{"Start":"06:54.185 ","End":"06:57.005","Text":"These fats are usually liquid and not solid."},{"Start":"06:57.005 ","End":"07:03.695","Text":"If so, how is it that margarine made out of oil from plants is solid?"},{"Start":"07:03.695 ","End":"07:06.485","Text":"The answer is that in the food industry,"},{"Start":"07:06.485 ","End":"07:11.555","Text":"oils are artificially hydrogenated to make them semi-solid."},{"Start":"07:11.555 ","End":"07:16.940","Text":"That\u0027s done by bubbling hydrogen gas through the oils to solidify them."},{"Start":"07:16.940 ","End":"07:20.270","Text":"We start with unsaturated fatty acids here,"},{"Start":"07:20.270 ","End":"07:23.840","Text":"but we don\u0027t have these hydrogens and therefore we have the angle,"},{"Start":"07:23.840 ","End":"07:27.440","Text":"and therefore we\u0027re talking about a liquid oil."},{"Start":"07:27.440 ","End":"07:30.620","Text":"While we bubble hydrogen atoms,"},{"Start":"07:30.620 ","End":"07:34.235","Text":"what we get is saturated fatty acids."},{"Start":"07:34.235 ","End":"07:37.625","Text":"These saturated acids are straight,"},{"Start":"07:37.625 ","End":"07:42.095","Text":"and therefore they\u0027re densely packed and they\u0027re more solid."},{"Start":"07:42.095 ","End":"07:45.305","Text":"But that\u0027s only half the problem here."},{"Start":"07:45.305 ","End":"07:47.656","Text":"During this hydrogenation,"},{"Start":"07:47.656 ","End":"07:51.725","Text":"a lot of times double bonds of the cis-conformation in the hydrocarbon chain,"},{"Start":"07:51.725 ","End":"07:55.595","Text":"may be converted to double bonds in the trans conformation."},{"Start":"07:55.595 ","End":"08:01.055","Text":"Cis and trans indicate the configuration of the molecule around the double bond."},{"Start":"08:01.055 ","End":"08:04.295","Text":"If the hydrogens are present in the same plane,"},{"Start":"08:04.295 ","End":"08:07.495","Text":"here, in the same plane, it\u0027s a cis fat."},{"Start":"08:07.495 ","End":"08:11.165","Text":"If the hydrogens are present in 2 different planes,"},{"Start":"08:11.165 ","End":"08:13.010","Text":"then we call it a trans fat."},{"Start":"08:13.010 ","End":"08:16.565","Text":"This trans fat is actually quite dangerous."},{"Start":"08:16.565 ","End":"08:18.590","Text":"The first thing we can see is that it\u0027s straight,"},{"Start":"08:18.590 ","End":"08:21.035","Text":"therefore it packs densely."},{"Start":"08:21.035 ","End":"08:25.790","Text":"The second thing is that all lipids are insoluble in water."},{"Start":"08:25.790 ","End":"08:28.430","Text":"In order to transport them through the blood,"},{"Start":"08:28.430 ","End":"08:30.665","Text":"it requires transport molecules."},{"Start":"08:30.665 ","End":"08:33.215","Text":"These are called lipoproteins."},{"Start":"08:33.215 ","End":"08:35.390","Text":"The low density lipoproteins,"},{"Start":"08:35.390 ","End":"08:38.660","Text":"or LDLs, are what we call bad cholesterol."},{"Start":"08:38.660 ","End":"08:42.485","Text":"They carry cholesterol from the liver to body cells."},{"Start":"08:42.485 ","End":"08:44.570","Text":"The high density lipoproteins,"},{"Start":"08:44.570 ","End":"08:47.110","Text":"the HDLs, are what we call good cholesterol."},{"Start":"08:47.110 ","End":"08:52.260","Text":"These collect cholesterol from the body\u0027s tissues and bring it back to the liver."},{"Start":"08:53.210 ","End":"08:58.210","Text":"An increase in trans fat in the diet may lead to an increase in LDL levels,"},{"Start":"08:58.210 ","End":"08:59.700","Text":"that\u0027s the bad cholesterol."},{"Start":"08:59.700 ","End":"09:05.870","Text":"The high LDL leads to plaque deposition in the arteries resulting in heart disease."},{"Start":"09:06.270 ","End":"09:09.950","Text":"The last point about fats and oils I wanted to mention,"},{"Start":"09:09.950 ","End":"09:11.980","Text":"are the essential fatty acids."},{"Start":"09:11.980 ","End":"09:14.200","Text":"By definition, these are the fatty acids that are"},{"Start":"09:14.200 ","End":"09:17.530","Text":"required but not synthesized by the human body."},{"Start":"09:17.530 ","End":"09:21.050","Text":"Therefore, they need to be supplemented through ingestion."},{"Start":"09:21.050 ","End":"09:23.725","Text":"We can either eat them through natural foods where they occur,"},{"Start":"09:23.725 ","End":"09:26.540","Text":"or to get them in these pills."},{"Start":"09:26.540 ","End":"09:32.785","Text":"2 examples will be the omega-6 fatty acid and the omega-3 fatty acids."},{"Start":"09:32.785 ","End":"09:38.030","Text":"In this section, we learned to explain the different roles of lipids."},{"Start":"09:38.030 ","End":"09:40.820","Text":"We described the 4 major types of lipids."},{"Start":"09:40.820 ","End":"09:46.040","Text":"We can now differentiate well between saturated and unsaturated fatty acids,"},{"Start":"09:46.040 ","End":"09:49.440","Text":"and we can also define cis and trans fats."},{"Start":"09:49.660 ","End":"09:53.690","Text":"In the next part, we\u0027re going to learn about waxes,"},{"Start":"09:53.690 ","End":"09:56.030","Text":"steroids, and phospholipids,"},{"Start":"09:56.030 ","End":"09:58.590","Text":"the 3 other lipid types."}],"ID":24126},{"Watched":false,"Name":"Lipids Part 2","Duration":"5m 33s","ChapterTopicVideoID":25434,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.170 ","End":"00:06.090","Text":"Hey, there. We\u0027re studying biological macromolecules."},{"Start":"00:06.090 ","End":"00:09.900","Text":"This is the second section speaking about lipids."},{"Start":"00:09.900 ","End":"00:15.615","Text":"Previously, we\u0027ve introduced lipids and spoke about the first type, fats and oils."},{"Start":"00:15.615 ","End":"00:18.675","Text":"In this part we\u0027ll be speaking about the other types,"},{"Start":"00:18.675 ","End":"00:22.830","Text":"waxes, phospholipids, and steroids."},{"Start":"00:22.830 ","End":"00:25.155","Text":"By the end of this section,"},{"Start":"00:25.155 ","End":"00:28.710","Text":"you\u0027ll be able to explain the role of phospholipids in cells,"},{"Start":"00:28.710 ","End":"00:31.395","Text":"define the basic structure of steroids,"},{"Start":"00:31.395 ","End":"00:35.339","Text":"and describe several functions of cholesterol."},{"Start":"00:35.339 ","End":"00:38.475","Text":"Let\u0027s speak about waxes then."},{"Start":"00:38.475 ","End":"00:45.109","Text":"Waxes are made of long fatty acid chains esterified to long-chain alcohols."},{"Start":"00:45.109 ","End":"00:48.140","Text":"This makes them solid at room temperature,"},{"Start":"00:48.140 ","End":"00:51.125","Text":"and hydrophobic, which means they repel water."},{"Start":"00:51.125 ","End":"00:54.905","Text":"Examples of waxes in nature would be;"},{"Start":"00:54.905 ","End":"00:57.095","Text":"the cells of the beehive,"},{"Start":"00:57.095 ","End":"01:00.425","Text":"waterproofing feathers especially in aquatic birds."},{"Start":"01:00.425 ","End":"01:03.605","Text":"As you can see here, that by secreting waxes onto the feather,"},{"Start":"01:03.605 ","End":"01:05.170","Text":"it turns to be waterproof,"},{"Start":"01:05.170 ","End":"01:07.375","Text":"the birds can stay dry."},{"Start":"01:07.375 ","End":"01:10.640","Text":"This waxy cuticle on the outer side of"},{"Start":"01:10.640 ","End":"01:14.060","Text":"the leaf helps the leaf to maintain its water inside,"},{"Start":"01:14.060 ","End":"01:15.730","Text":"so this water proofs the leaf,"},{"Start":"01:15.730 ","End":"01:17.480","Text":"so it doesn\u0027t lose its water."},{"Start":"01:17.480 ","End":"01:20.825","Text":"The third group of lipids are the phospholipids."},{"Start":"01:20.825 ","End":"01:24.440","Text":"Phospholipids make up the matrix of cell membranes."},{"Start":"01:24.440 ","End":"01:27.815","Text":"Here we have a cell, and you can see the outer membrane here"},{"Start":"01:27.815 ","End":"01:31.610","Text":"is made out of a double layer of these interesting molecules."},{"Start":"01:31.610 ","End":"01:34.655","Text":"Let\u0027s have a close look at this molecule."},{"Start":"01:34.655 ","End":"01:37.744","Text":"We have the backbone made of glycerol,"},{"Start":"01:37.744 ","End":"01:41.320","Text":"sometimes substituted by sphingosine."},{"Start":"01:41.320 ","End":"01:45.350","Text":"2 fatty acid chains extend from this backbone."},{"Start":"01:45.350 ","End":"01:46.700","Text":"In this illustration,"},{"Start":"01:46.700 ","End":"01:48.080","Text":"1 of them is saturated,"},{"Start":"01:48.080 ","End":"01:52.325","Text":"and the other is unsaturated giving it this angle here."},{"Start":"01:52.325 ","End":"01:56.195","Text":"Also connected to the backbone is a phosphate group."},{"Start":"01:56.195 ","End":"01:59.870","Text":"The phosphate group is usually modified by addition of"},{"Start":"01:59.870 ","End":"02:03.545","Text":"charged or polar groups, choline or serine."},{"Start":"02:03.545 ","End":"02:06.460","Text":"This R here stands for 1 of these groups."},{"Start":"02:06.460 ","End":"02:12.805","Text":"These charged or polar groups turn the head to be hydrophilic or water-loving,"},{"Start":"02:12.805 ","End":"02:18.430","Text":"while the fatty acid chains turn the tails to be hydrophobic."},{"Start":"02:18.430 ","End":"02:22.530","Text":"This is especially important for the phospholipids job in"},{"Start":"02:22.530 ","End":"02:27.400","Text":"the matrix of cell membranes. Why is that?"},{"Start":"02:27.440 ","End":"02:33.070","Text":"Well, if you drop into this cup of water a hydrophobic substance such as oil,"},{"Start":"02:33.070 ","End":"02:39.040","Text":"the water will repel it and we\u0027ll see it\u0027ll aggregate into its own little groups."},{"Start":"02:39.040 ","End":"02:46.605","Text":"But what happens when you drop a molecule that\u0027s half hydrophilic and half hydrophobic?"},{"Start":"02:46.605 ","End":"02:51.725","Text":"Well, these phospholipids adjust that and when you drop them into a cup of water,"},{"Start":"02:51.725 ","End":"02:54.775","Text":"they tend to find 2 stable shapes."},{"Start":"02:54.775 ","End":"03:02.140","Text":"The first are these balls with water-loving heads facing the outside of the bowl,"},{"Start":"03:02.140 ","End":"03:05.870","Text":"and the inside is a hydrophobic region of the tails."},{"Start":"03:05.870 ","End":"03:09.200","Text":"But an even more stable structure would be the double layer."},{"Start":"03:09.200 ","End":"03:12.320","Text":"Here we have a whole double layer which really just extends in"},{"Start":"03:12.320 ","End":"03:18.820","Text":"a circle or in a whole sphere."},{"Start":"03:18.820 ","End":"03:22.280","Text":"The outside of it is water-loving,"},{"Start":"03:22.280 ","End":"03:29.490","Text":"the aqueous area outside of the cell or this cup of water."},{"Start":"03:29.490 ","End":"03:33.570","Text":"Also on the inside you get a sphere of water,"},{"Start":"03:33.570 ","End":"03:37.900","Text":"and we have your whole hydrophobic region in-between where the tails are."},{"Start":"03:37.900 ","End":"03:40.495","Text":"That is exactly what happens in the cell membrane."},{"Start":"03:40.495 ","End":"03:41.770","Text":"We have a double layer,"},{"Start":"03:41.770 ","End":"03:43.825","Text":"a bilayer, of phospholipids,"},{"Start":"03:43.825 ","End":"03:49.085","Text":"and the hydrophilic head group of the phospholipids face the aqueous solution."},{"Start":"03:49.085 ","End":"03:52.690","Text":"Here we have an aqueous solution inside the cell,"},{"Start":"03:52.690 ","End":"03:56.380","Text":"and here we have aqueous solution outside the cell."},{"Start":"03:56.380 ","End":"04:00.710","Text":"The hydrophobic tails are sequestered in the middle of the bilayer."},{"Start":"04:00.710 ","End":"04:05.920","Text":"Here we have the hydrophobic or water repelling region inside here."},{"Start":"04:05.920 ","End":"04:09.490","Text":"Last but not least, are the steroids."},{"Start":"04:09.490 ","End":"04:15.560","Text":"The structure of steroids is usually 4 fused carbon rings, as you can see here."},{"Start":"04:15.560 ","End":"04:18.215","Text":"Although very different from the other lipid types,"},{"Start":"04:18.215 ","End":"04:24.530","Text":"steroids are categorized as lipids mainly because they\u0027re hydrophobic or water repelling."},{"Start":"04:24.530 ","End":"04:28.750","Text":"Many of the steroids have an OH functional group."},{"Start":"04:28.750 ","End":"04:31.250","Text":"This classifies them as alcohols."},{"Start":"04:31.250 ","End":"04:34.695","Text":"Steroids that are alcohols are also known as sterols."},{"Start":"04:34.695 ","End":"04:38.734","Text":"Some of them have a short tail like this cholesterol."},{"Start":"04:38.734 ","End":"04:41.030","Text":"As a nice example of steroids,"},{"Start":"04:41.030 ","End":"04:42.934","Text":"let\u0027s speak about this cholesterol."},{"Start":"04:42.934 ","End":"04:46.925","Text":"The cholesterol helps to maintain the membrane fluidity."},{"Start":"04:46.925 ","End":"04:50.180","Text":"Between the phospholipids and the cell membrane,"},{"Start":"04:50.180 ","End":"04:52.640","Text":"we find a lot of cholesterol molecules too."},{"Start":"04:52.640 ","End":"04:55.465","Text":"The cholesterol is synthesized internally."},{"Start":"04:55.465 ","End":"05:00.185","Text":"It\u0027s also used as a precursor for other steroid hormones,"},{"Start":"05:00.185 ","End":"05:02.975","Text":"such as testosterone or estrogen,"},{"Start":"05:02.975 ","End":"05:05.135","Text":"otherwise known as the sex hormones."},{"Start":"05:05.135 ","End":"05:11.150","Text":"These hormones dictate whether the growing fetus will become a male or a female."},{"Start":"05:11.150 ","End":"05:18.720","Text":"Cholesterol is also associated with cardiovascular diseases such as clogged arteries."},{"Start":"05:18.910 ","End":"05:21.710","Text":"Now that we\u0027ve spoken about lipids,"},{"Start":"05:21.710 ","End":"05:24.970","Text":"you can explain the role of phospholipids in cells,"},{"Start":"05:24.970 ","End":"05:27.715","Text":"define the basic structure of steroids,"},{"Start":"05:27.715 ","End":"05:31.160","Text":"and describe several functions of cholesterol."},{"Start":"05:31.160 ","End":"05:33.930","Text":"See you in the next section."}],"ID":26261},{"Watched":false,"Name":"Carbohydrates","Duration":"7m 1s","ChapterTopicVideoID":23285,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.260 ","End":"00:04.575","Text":"Hi, we\u0027re learning about biological macromolecules,"},{"Start":"00:04.575 ","End":"00:07.365","Text":"and this section is all about carbohydrates."},{"Start":"00:07.365 ","End":"00:09.075","Text":"By the end of this section,"},{"Start":"00:09.075 ","End":"00:12.810","Text":"you\u0027ll be able to discuss the role of carbohydrates in cells"},{"Start":"00:12.810 ","End":"00:16.740","Text":"and in the extracellular materials of animals and plants."},{"Start":"00:16.740 ","End":"00:18.990","Text":"You\u0027ll be able to explain the classifications of"},{"Start":"00:18.990 ","End":"00:21.900","Text":"carbohydrates and list common monosaccharides,"},{"Start":"00:21.900 ","End":"00:25.150","Text":"disaccharides, and polysaccharides."},{"Start":"00:25.610 ","End":"00:30.315","Text":"What are carbohydrates? By definition,"},{"Start":"00:30.315 ","End":"00:35.100","Text":"carbs are a group of macromolecules that are a vital energy source for the cell,"},{"Start":"00:35.100 ","End":"00:37.905","Text":"and provide structural support to plant cells,"},{"Start":"00:37.905 ","End":"00:40.140","Text":"fungi, and arthropods,"},{"Start":"00:40.140 ","End":"00:42.025","Text":"which include, by the way;"},{"Start":"00:42.025 ","End":"00:49.430","Text":"spiders, insects,"},{"Start":"00:49.430 ","End":"00:53.730","Text":"and crabs."},{"Start":"00:53.770 ","End":"00:57.205","Text":"Carbohydrates have several functions."},{"Start":"00:57.205 ","End":"01:01.940","Text":"First, they\u0027re used as a main source of energy in many diets,"},{"Start":"01:01.940 ","End":"01:05.465","Text":"including foods with starches and sugars."},{"Start":"01:05.465 ","End":"01:09.199","Text":"They\u0027re also essential constituents of important molecules,"},{"Start":"01:09.199 ","End":"01:11.855","Text":"such as pentose in nucleic acids."},{"Start":"01:11.855 ","End":"01:13.670","Text":"Here we have DNA and nucleic acid,"},{"Start":"01:13.670 ","End":"01:18.440","Text":"and we can see that the structural backbone is made of sugar and phosphate."},{"Start":"01:18.440 ","End":"01:22.440","Text":"These sugars are actually carbohydrates."},{"Start":"01:22.440 ","End":"01:27.545","Text":"Third, they\u0027re used as structural components in cells such as plant cells."},{"Start":"01:27.545 ","End":"01:30.095","Text":"Fourth, they\u0027re used for protective covering,"},{"Start":"01:30.095 ","End":"01:34.535","Text":"for example, chitin and all arthropods outer armor."},{"Start":"01:34.535 ","End":"01:38.090","Text":"All carbohydrates are classified either as"},{"Start":"01:38.090 ","End":"01:43.205","Text":"monosaccharides, disaccharides, or polysaccharides,"},{"Start":"01:43.205 ","End":"01:45.525","Text":"meaning single sugars,"},{"Start":"01:45.525 ","End":"01:47.264","Text":"for example, glucose,"},{"Start":"01:47.264 ","End":"01:49.395","Text":"which includes just 1 sugar molecule,"},{"Start":"01:49.395 ","End":"01:52.380","Text":"disaccharides, meaning double sugar,"},{"Start":"01:52.380 ","End":"01:54.380","Text":"for example; maltose,"},{"Start":"01:54.380 ","End":"01:56.135","Text":"which is composed of"},{"Start":"01:56.135 ","End":"02:00.875","Text":"double glucose molecules connected to each other by a glycosidic bond,"},{"Start":"02:00.875 ","End":"02:04.165","Text":"or polysaccharides, meaning many sugars,"},{"Start":"02:04.165 ","End":"02:08.380","Text":"which in this example we have many molecules of glucose connected to each other"},{"Start":"02:08.380 ","End":"02:13.100","Text":"by glycosidic bonds, making cellulose."},{"Start":"02:13.100 ","End":"02:15.750","Text":"Monosaccharides, by definition,"},{"Start":"02:15.750 ","End":"02:16.950","Text":"are single sugars,"},{"Start":"02:16.950 ","End":"02:19.530","Text":"such as this glucose molecule."},{"Start":"02:19.530 ","End":"02:22.330","Text":"They may exist as rings or as chains."},{"Start":"02:22.330 ","End":"02:24.925","Text":"So here we have a chain and here we have a ring."},{"Start":"02:24.925 ","End":"02:30.085","Text":"You can see that the oxygen and carbon 5 connects,"},{"Start":"02:30.085 ","End":"02:35.515","Text":"making a covalent bond with the carbon number 1 here, making a ring."},{"Start":"02:35.515 ","End":"02:40.540","Text":"This glucose molecule is constantly changing between these 2 states."},{"Start":"02:40.540 ","End":"02:43.540","Text":"Many of these monosaccharides are sweet."},{"Start":"02:43.540 ","End":"02:45.590","Text":"Examples would be glucose."},{"Start":"02:45.590 ","End":"02:48.774","Text":"We see here, galactose and fructose."},{"Start":"02:48.774 ","End":"02:52.430","Text":"Glucose is 1 of the main sources of energy in the human body."},{"Start":"02:52.430 ","End":"02:56.240","Text":"During cellular respiration it\u0027s used to create ATP."},{"Start":"02:56.240 ","End":"03:00.380","Text":"Galactose is part of the disaccharide lactose found in milk,"},{"Start":"03:00.380 ","End":"03:03.270","Text":"and fructose is found in fruits."},{"Start":"03:04.240 ","End":"03:07.970","Text":"Monosaccharides are classified based on the position of"},{"Start":"03:07.970 ","End":"03:11.795","Text":"the carbonyl group and the number of carbons in the backbone."},{"Start":"03:11.795 ","End":"03:15.695","Text":"Aldoses have the carbonyl group at the end of the chain,"},{"Start":"03:15.695 ","End":"03:20.005","Text":"while ketoses have the carbonyl group in the middle of the chain."},{"Start":"03:20.005 ","End":"03:23.025","Text":"Depending on the number of carbons in the sugar,"},{"Start":"03:23.025 ","End":"03:26.700","Text":"they can be trioses if they have 3 carbons."},{"Start":"03:26.700 ","End":"03:30.380","Text":"They can be pentoses if they have 5 carbons,"},{"Start":"03:30.380 ","End":"03:34.380","Text":"or hexoses, if they have 6 carbons."},{"Start":"03:35.500 ","End":"03:38.330","Text":"Monosaccharides are linked by"},{"Start":"03:38.330 ","End":"03:42.694","Text":"glycosidic bonds that are formed as a result of dehydration reactions."},{"Start":"03:42.694 ","End":"03:49.790","Text":"This forms disaccharides and also eliminates 1 molecule of water for each bond is formed."},{"Start":"03:49.790 ","End":"03:53.840","Text":"In this example, we have a monomer of glucose and"},{"Start":"03:53.840 ","End":"03:57.140","Text":"the monomer fructose, both monosaccharides."},{"Start":"03:57.140 ","End":"04:00.245","Text":"We\u0027re going to see now how the glycosidic bond is formed."},{"Start":"04:00.245 ","End":"04:05.145","Text":"So take a good look here and we have our glycosidic bond."},{"Start":"04:05.145 ","End":"04:08.960","Text":"We also lost 1 molecule of water."},{"Start":"04:08.960 ","End":"04:10.100","Text":"Where did that molecule come from?"},{"Start":"04:10.100 ","End":"04:16.175","Text":"Let\u0027s take a look again. Here we had an extra oxygen atom and 2 extra hydrogen atoms,"},{"Start":"04:16.175 ","End":"04:18.890","Text":"which form that water molecule."},{"Start":"04:18.890 ","End":"04:24.290","Text":"Joining glucose and fructose gave the disaccharide sucrose,"},{"Start":"04:24.290 ","End":"04:27.455","Text":"commonly known as kitchen sugar."},{"Start":"04:27.455 ","End":"04:30.185","Text":"Other examples would be lactose,"},{"Start":"04:30.185 ","End":"04:33.830","Text":"found in milk composed of galactose and glucose subunits,"},{"Start":"04:33.830 ","End":"04:39.154","Text":"and maltose, which is 2 combining glucose molecules."},{"Start":"04:39.154 ","End":"04:45.320","Text":"Polysaccharides are long chains of monosaccharides linked by glycosidic bonds."},{"Start":"04:45.320 ","End":"04:47.735","Text":"The long polysaccharide chains,"},{"Start":"04:47.735 ","End":"04:50.815","Text":"maybe branched or unbranched."},{"Start":"04:50.815 ","End":"04:56.389","Text":"Amylopectin and amylose are 2 different forms of starch."},{"Start":"04:56.389 ","End":"05:03.020","Text":"Amylose is composed of unbranched chains of glucose monomers connected by Alpha 1,"},{"Start":"05:03.020 ","End":"05:05.840","Text":"4 glycosidic linkages, meaning that"},{"Start":"05:05.840 ","End":"05:11.380","Text":"carbon number 1 connects with carbon number 4 in the following glucose subunits."},{"Start":"05:11.380 ","End":"05:16.610","Text":"Amylopectin is composed of branched chains of glucose monomers connected by Alpha 1,"},{"Start":"05:16.610 ","End":"05:18.220","Text":"4 glycosidic bonds,"},{"Start":"05:18.220 ","End":"05:20.400","Text":"and also Alpha 1,"},{"Start":"05:20.400 ","End":"05:24.035","Text":"6 bonds, giving it this branched structure."},{"Start":"05:24.035 ","End":"05:26.315","Text":"Because of the way the subunits are joined,"},{"Start":"05:26.315 ","End":"05:30.110","Text":"the glucose chains have a helical structure."},{"Start":"05:30.110 ","End":"05:35.315","Text":"Polysaccharides are the storage forms of glucose in plants and animals."},{"Start":"05:35.315 ","End":"05:39.335","Text":"The storage of glucose in the form of polymers like starch or glycogen,"},{"Start":"05:39.335 ","End":"05:42.155","Text":"make it slightly less accessible for metabolism."},{"Start":"05:42.155 ","End":"05:44.965","Text":"However, it prevents it from leaking out of the cell,"},{"Start":"05:44.965 ","End":"05:49.730","Text":"or creating a high osmotic pressure that could cause excessive water uptake by the cell."},{"Start":"05:49.730 ","End":"05:52.415","Text":"Examples for polysaccharides, well,"},{"Start":"05:52.415 ","End":"05:56.980","Text":"first it will be starch in plant cells like amylopectin,"},{"Start":"05:56.980 ","End":"06:01.580","Text":"which is the way plants store their excess glucose molecules,"},{"Start":"06:01.580 ","End":"06:05.175","Text":"and glycogen in humans and other vertebrates."},{"Start":"06:05.175 ","End":"06:08.080","Text":"Similarly structured like amylopectin,"},{"Start":"06:08.080 ","End":"06:11.170","Text":"but even more highly branched."},{"Start":"06:11.170 ","End":"06:14.965","Text":"Glycogen is the animal equivalent of starch."},{"Start":"06:14.965 ","End":"06:19.690","Text":"The highly branched molecule is usually stored in the liver or in muscle cells."},{"Start":"06:19.690 ","End":"06:22.270","Text":"Whenever blood glucose levels decrease,"},{"Start":"06:22.270 ","End":"06:27.745","Text":"glycogen is broken down to release glucose in a process known as glycogenolysis."},{"Start":"06:27.745 ","End":"06:30.325","Text":"Our third example is cellulose,"},{"Start":"06:30.325 ","End":"06:33.130","Text":"the most abundant natural biopolymer."},{"Start":"06:33.130 ","End":"06:36.655","Text":"The cell wall of plants is mostly made of cellulose."},{"Start":"06:36.655 ","End":"06:39.485","Text":"This provides structural support to the cell."},{"Start":"06:39.485 ","End":"06:43.250","Text":"Wooden paper are mostly cellulose in nature."},{"Start":"06:43.250 ","End":"06:46.370","Text":"We have successfully learned about carbohydrates."},{"Start":"06:46.370 ","End":"06:49.100","Text":"We now can discuss the role of carbohydrates in cells"},{"Start":"06:49.100 ","End":"06:52.160","Text":"and the extracellular materials of animals and plants."},{"Start":"06:52.160 ","End":"06:55.220","Text":"We can explain the classifications of carbohydrates,"},{"Start":"06:55.220 ","End":"06:57.505","Text":"and we can list the common monosaccharides,"},{"Start":"06:57.505 ","End":"07:01.090","Text":"disaccharides, and polysaccharides."}],"ID":24124},{"Watched":false,"Name":"Nucleic Acids","Duration":"11m 45s","ChapterTopicVideoID":23288,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.410 ","End":"00:03.930","Text":"We\u0027re learning about biological macromolecules."},{"Start":"00:03.930 ","End":"00:05.010","Text":"In this section,"},{"Start":"00:05.010 ","End":"00:06.990","Text":"we\u0027ll speak about nucleic acids."},{"Start":"00:06.990 ","End":"00:08.640","Text":"By the end of this section,"},{"Start":"00:08.640 ","End":"00:10.890","Text":"you\u0027ll be able to describe the structure of"},{"Start":"00:10.890 ","End":"00:14.835","Text":"nucleic acids and define the 2 types of nucleic acids."},{"Start":"00:14.835 ","End":"00:17.775","Text":"Explain the structure and role of DNA,"},{"Start":"00:17.775 ","End":"00:21.430","Text":"and explain the structure and roles of RNA."},{"Start":"00:21.860 ","End":"00:27.545","Text":"By definition, nucleic acids are molecules made up of nucleotides."},{"Start":"00:27.545 ","End":"00:33.690","Text":"These molecules direct cellular activities such as cell division and protein synthesis."},{"Start":"00:34.390 ","End":"00:38.550","Text":"What are the functions of nucleic acids?"},{"Start":"00:38.800 ","End":"00:43.085","Text":"Nucleic acids are information storage molecules."},{"Start":"00:43.085 ","End":"00:46.250","Text":"They provide the directions for building proteins."},{"Start":"00:46.250 ","End":"00:51.405","Text":"There are 2 types of nucleic acids, DNA and RNA."},{"Start":"00:51.405 ","End":"00:58.520","Text":"DNA stands for deoxyribonucleic acid and RNA stands for ribonucleic acid."},{"Start":"00:58.520 ","End":"01:02.280","Text":"If you\u0027ll notice the difference between these 2 molecules is in"},{"Start":"01:02.280 ","End":"01:06.990","Text":"this deoxy and soon we\u0027ll see why and what this means."},{"Start":"01:07.030 ","End":"01:10.225","Text":"What is the structure of nucleic acids?"},{"Start":"01:10.225 ","End":"01:13.585","Text":"Nucleic acids are polymers of nucleotides."},{"Start":"01:13.585 ","End":"01:15.475","Text":"This is a nucleotide,"},{"Start":"01:15.475 ","End":"01:18.475","Text":"and each nucleotide is made up of a pentose sugar."},{"Start":"01:18.475 ","End":"01:19.990","Text":"We see this is the pentose sugar."},{"Start":"01:19.990 ","End":"01:21.400","Text":"Pentose, I remind you,"},{"Start":"01:21.400 ","End":"01:24.080","Text":"is that 5 carbon-based sugar we have here,"},{"Start":"01:24.080 ","End":"01:26.280","Text":"5 carbon molecules in this sugar,"},{"Start":"01:26.280 ","End":"01:31.020","Text":"a nitrogenous base, and a phosphate group."},{"Start":"01:31.020 ","End":"01:32.815","Text":"Here we have 1 phosphate group,"},{"Start":"01:32.815 ","End":"01:35.425","Text":"but we can have more of them too."},{"Start":"01:35.425 ","End":"01:40.910","Text":"The carbon residues of the pentose are numbered 1\u0027 through 5\u0027."},{"Start":"01:40.910 ","End":"01:44.535","Text":"Here we see then, this carbon is the 1\u0027 carbon,"},{"Start":"01:44.535 ","End":"01:46.560","Text":"2\u0027 carbon, 3\u0027,"},{"Start":"01:46.560 ","End":"01:49.410","Text":"4\u0027, and 5\u0027."},{"Start":"01:49.410 ","End":"01:54.695","Text":"This is especially important in DNA because when a polynucleotide is formed,"},{"Start":"01:54.695 ","End":"01:58.370","Text":"that means a molecule made of many nucleotides."},{"Start":"01:58.370 ","End":"02:00.680","Text":"When a polynucleotide is formed,"},{"Start":"02:00.680 ","End":"02:04.040","Text":"the 5\u0027 phosphate of the incoming nucleotide"},{"Start":"02:04.040 ","End":"02:09.140","Text":"attaches to the 3\u0027 hydroxyl group at the end of the growing chain."},{"Start":"02:09.140 ","End":"02:11.090","Text":"Let\u0027s see how that looks."},{"Start":"02:11.090 ","End":"02:13.280","Text":"If we have our first nucleotide here,"},{"Start":"02:13.280 ","End":"02:16.215","Text":"make it smaller to make room for other ones."},{"Start":"02:16.215 ","End":"02:20.065","Text":"This is the 5\u0027 carbon with a phosphate group,"},{"Start":"02:20.065 ","End":"02:23.900","Text":"and here we have the 3\u0027 carbon and the next nucleotide"},{"Start":"02:23.900 ","End":"02:29.060","Text":"attaches the phosphate to the 3\u0027 carbon."},{"Start":"02:29.060 ","End":"02:31.310","Text":"What we have actually, since this is"},{"Start":"02:31.310 ","End":"02:35.900","Text":"the 5\u0027 carbon connected to the phosphate and we connect more with them."},{"Start":"02:35.900 ","End":"02:40.775","Text":"Essentially, we have a long molecule which is a polynucleotide."},{"Start":"02:40.775 ","End":"02:43.460","Text":"What\u0027s important here is that as directional, we have 1 side,"},{"Start":"02:43.460 ","End":"02:45.095","Text":"that\u0027s the 5\u0027 side,"},{"Start":"02:45.095 ","End":"02:48.450","Text":"and the other side is the 3\u0027 side."},{"Start":"02:49.330 ","End":"02:52.160","Text":"As you mentioned earlier, there are 2 types of"},{"Start":"02:52.160 ","End":"02:54.980","Text":"pentose sugars that are found in the nucleotides."},{"Start":"02:54.980 ","End":"02:57.695","Text":"Deoxyribose found in DNA,"},{"Start":"02:57.695 ","End":"02:59.720","Text":"and ribose found in RNA."},{"Start":"02:59.720 ","End":"03:04.050","Text":"Here we can see the ribose and the deoxyribose."},{"Start":"03:04.280 ","End":"03:09.070","Text":"We mentioned that there are 2 types of nucleic acids, DNA and RNA,"},{"Start":"03:09.070 ","End":"03:13.165","Text":"and that these 2 acids are differentiated by the pentose sugar,"},{"Start":"03:13.165 ","End":"03:15.470","Text":"deoxyribose found in DNA,"},{"Start":"03:15.470 ","End":"03:17.785","Text":"and the ribose found in RNA."},{"Start":"03:17.785 ","End":"03:19.300","Text":"You see the difference here is that, well,"},{"Start":"03:19.300 ","End":"03:24.100","Text":"they\u0027re both pentose is they\u0027re both sugar with 5 carbons."},{"Start":"03:24.100 ","End":"03:25.515","Text":"We have here 1,"},{"Start":"03:25.515 ","End":"03:26.640","Text":"2, 3, 4,"},{"Start":"03:26.640 ","End":"03:27.885","Text":"and here\u0027s number 5."},{"Start":"03:27.885 ","End":"03:30.060","Text":"We have here also 1, 2, 3, 4,"},{"Start":"03:30.060 ","End":"03:32.290","Text":"and 5, 5 carbons."},{"Start":"03:32.290 ","End":"03:34.525","Text":"These are pentose is called ribose."},{"Start":"03:34.525 ","End":"03:37.960","Text":"This is the regular ribose,"},{"Start":"03:37.960 ","End":"03:42.280","Text":"while this ribose lacks the oxygen on carbon number 2,"},{"Start":"03:42.280 ","End":"03:47.195","Text":"so it\u0027s deoxyribose because it is lacking the oxygen."},{"Start":"03:47.195 ","End":"03:53.300","Text":"That is the difference between RNA nucleotides and DNA nucleotides."},{"Start":"03:53.430 ","End":"03:56.110","Text":"Since we don\u0027t see the oxygen here,"},{"Start":"03:56.110 ","End":"04:01.470","Text":"it is DNA if we would see here in hydroxyl group OH,"},{"Start":"04:01.470 ","End":"04:03.790","Text":"so this would be RNA."},{"Start":"04:04.550 ","End":"04:10.320","Text":"The nucleotide includes 1 of several nitrogenous bases,"},{"Start":"04:10.320 ","End":"04:17.000","Text":"and these bases can be divided into 2 categories, purines and pyrimidines."},{"Start":"04:18.030 ","End":"04:23.605","Text":"Purines have a double ring structure as the adenine and guanine here."},{"Start":"04:23.605 ","End":"04:31.990","Text":"You can see, symbol by the A and the G. Pyrimidines on the other hand,"},{"Start":"04:31.990 ","End":"04:33.385","Text":"have a single ring."},{"Start":"04:33.385 ","End":"04:36.155","Text":"Here we have a single ring structure."},{"Start":"04:36.155 ","End":"04:40.995","Text":"The 3 pyrimidines that we might meet are the cytosine abbreviated with a C,"},{"Start":"04:40.995 ","End":"04:43.905","Text":"the thiamine abbreviated by T,"},{"Start":"04:43.905 ","End":"04:45.960","Text":"and the uracil abbreviated with"},{"Start":"04:45.960 ","End":"04:55.135","Text":"a U. Nucleotide monomers are linked into long chains, as we saw earlier."},{"Start":"04:55.135 ","End":"04:57.340","Text":"This is the 5\u0027 side,"},{"Start":"04:57.340 ","End":"04:59.769","Text":"and this is the 3\u0027 side,"},{"Start":"04:59.769 ","End":"05:02.150","Text":"it is directional, of course."},{"Start":"05:03.320 ","End":"05:06.970","Text":"A sugar phosphate bone joins them together."},{"Start":"05:06.970 ","End":"05:09.100","Text":"We have here the phosphate connecting to the sugar,"},{"Start":"05:09.100 ","End":"05:11.050","Text":"connected to the phosphate, connected to the sugar,"},{"Start":"05:11.050 ","End":"05:12.320","Text":"connected to the phosphate."},{"Start":"05:12.320 ","End":"05:15.020","Text":"This is the backbone of the polynucleotide."},{"Start":"05:15.020 ","End":"05:20.940","Text":"These chains are called polynucleotides or DNA strands."},{"Start":"05:21.820 ","End":"05:25.210","Text":"What are the properties of DNA?"},{"Start":"05:25.210 ","End":"05:28.580","Text":"DNA carries the genetic blueprint of the cell,"},{"Start":"05:28.580 ","End":"05:31.310","Text":"and is passed on from parents to offspring."},{"Start":"05:31.310 ","End":"05:35.120","Text":"It\u0027s has a double-helical structure with 2 strands."},{"Start":"05:35.120 ","End":"05:37.940","Text":"These strands run in opposite directions."},{"Start":"05:37.940 ","End":"05:40.550","Text":"They\u0027re connected to each other by hydrogen bonds,"},{"Start":"05:40.550 ","End":"05:43.560","Text":"and they are complimentary to each other."},{"Start":"05:45.890 ","End":"05:51.375","Text":"Each DNA nucleotide has 1 of the following bases,"},{"Start":"05:51.375 ","End":"05:54.450","Text":"adenine abbreviated with an A,"},{"Start":"05:54.450 ","End":"05:56.805","Text":"guanine abbreviated by G,"},{"Start":"05:56.805 ","End":"05:58.905","Text":"thymine abbreviated with a T,"},{"Start":"05:58.905 ","End":"06:02.630","Text":"or a cytosine abbreviated with a C. Since"},{"Start":"06:02.630 ","End":"06:07.325","Text":"the sugar phosphate backbone is identical between the different molecules,"},{"Start":"06:07.325 ","End":"06:13.124","Text":"it\u0027s easier to depict the DNA molecule as a long strand"},{"Start":"06:13.124 ","End":"06:19.560","Text":"while the only difference between the nucleotides are the bases here T,"},{"Start":"06:19.560 ","End":"06:22.320","Text":"A, C, G, or T. Therefore,"},{"Start":"06:22.320 ","End":"06:24.430","Text":"we can look at it as a code."},{"Start":"06:24.430 ","End":"06:27.350","Text":"Let\u0027s have a look at the strands."},{"Start":"06:27.350 ","End":"06:32.180","Text":"We have here 1 strand running from 5\u0027 to 3\u0027."},{"Start":"06:32.180 ","End":"06:35.600","Text":"This is the phosphate sugar backbone."},{"Start":"06:35.600 ","End":"06:39.705","Text":"We have here T for thymine,"},{"Start":"06:39.705 ","End":"06:41.835","Text":"and we have here G for guanine."},{"Start":"06:41.835 ","End":"06:45.890","Text":"On the opposite strand running from 5 to 3,"},{"Start":"06:45.890 ","End":"06:48.875","Text":"here we have the opposite directions."},{"Start":"06:48.875 ","End":"06:51.680","Text":"We have here other bases."},{"Start":"06:51.680 ","End":"06:56.210","Text":"Now, the bases are always paired with a specific bases."},{"Start":"06:56.210 ","End":"06:58.775","Text":"The adenine is always paired with thymine,"},{"Start":"06:58.775 ","End":"07:01.325","Text":"and guanine is always paired with cytosine."},{"Start":"07:01.325 ","End":"07:04.680","Text":"So you always going to see G\u0027s and C\u0027s together."},{"Start":"07:04.680 ","End":"07:06.975","Text":"We will always see the A and the T together."},{"Start":"07:06.975 ","End":"07:10.520","Text":"The way they are connected is by hydrogen bonds."},{"Start":"07:10.520 ","End":"07:14.224","Text":"Therefore, given 1 strand,"},{"Start":"07:14.224 ","End":"07:17.520","Text":"I can already tell you what\u0027s going to be on the other strand."},{"Start":"07:17.660 ","End":"07:21.060","Text":"We have here 1 strand with a T, A, C,"},{"Start":"07:21.060 ","End":"07:23.910","Text":"G, T running from 5\u0027 to 3\u0027."},{"Start":"07:23.910 ","End":"07:25.230","Text":"We already know that the T,"},{"Start":"07:25.230 ","End":"07:26.850","Text":"we\u0027re going to have you an A other side."},{"Start":"07:26.850 ","End":"07:29.720","Text":"Here we\u0027re going to see a T. Here we\u0027re going see"},{"Start":"07:29.720 ","End":"07:33.425","Text":"G paired with a C. Here we\u0027ll see a C and here we\u0027ll see an A."},{"Start":"07:33.425 ","End":"07:35.030","Text":"Let\u0027s just check that, we\u0027re right."},{"Start":"07:35.030 ","End":"07:40.860","Text":"Here we have the A and C connected to the G. G connected to C,"},{"Start":"07:40.860 ","End":"07:48.430","Text":"T and A are paired and A and T. The 2 strands of DNA joined together with hydrogen bonds."},{"Start":"07:48.430 ","End":"07:53.385","Text":"Here, let\u0027s have a larger look, a longer strand."},{"Start":"07:53.385 ","End":"07:57.735","Text":"The 2 strands twist to form a double-helical shape."},{"Start":"07:57.735 ","End":"08:01.740","Text":"Here we have each strand and we"},{"Start":"08:01.740 ","End":"08:05.480","Text":"have the opposite strand running in the opposite direction."},{"Start":"08:05.480 ","End":"08:08.105","Text":"This is running from 5-3."},{"Start":"08:08.105 ","End":"08:10.420","Text":"This 1 is running from 5-3 this way,"},{"Start":"08:10.420 ","End":"08:12.360","Text":"here we go, is the other 1,"},{"Start":"08:12.360 ","End":"08:14.010","Text":"and we can see they are paired,"},{"Start":"08:14.010 ","End":"08:19.354","Text":"they connected with hydrogen bonds and they form these grooves."},{"Start":"08:19.354 ","End":"08:23.360","Text":"This is the smaller groove in the area between"},{"Start":"08:23.360 ","End":"08:28.750","Text":"the connections and this is the wine groove."},{"Start":"08:29.210 ","End":"08:33.045","Text":"What is RNA and what is its function?"},{"Start":"08:33.045 ","End":"08:37.135","Text":"RNA as we said, is made of a pentose sugar, the ribose."},{"Start":"08:37.135 ","End":"08:40.104","Text":"This time it has the oxygen,"},{"Start":"08:40.104 ","End":"08:42.265","Text":"a nitrogenous base,"},{"Start":"08:42.265 ","End":"08:44.870","Text":"and a phosphate group, 1 or more."},{"Start":"08:44.870 ","End":"08:49.530","Text":"The RNA, unlike the DNA, is single-stranded."},{"Start":"08:49.900 ","End":"08:56.044","Text":"Another difference between DNA and RNA is that RNA includes the base uracil,"},{"Start":"08:56.044 ","End":"08:58.955","Text":"abbreviated by a U instead of thymine,"},{"Start":"08:58.955 ","End":"09:03.695","Text":"abbreviated by a T. The 4 bases that we might see in RNA,"},{"Start":"09:03.695 ","End":"09:06.710","Text":"would be the adenine A, guanine G,"},{"Start":"09:06.710 ","End":"09:12.365","Text":"uracil U, and cytosine C. Just like in DNA,"},{"Start":"09:12.365 ","End":"09:15.860","Text":"G and C are paired."},{"Start":"09:15.860 ","End":"09:17.150","Text":"Here instead of A and T,"},{"Start":"09:17.150 ","End":"09:21.090","Text":"we have A that pairs with U."},{"Start":"09:21.790 ","End":"09:24.785","Text":"What is the function of RNA?"},{"Start":"09:24.785 ","End":"09:28.940","Text":"RNA is involved in protein synthesis and regulation."},{"Start":"09:28.940 ","End":"09:31.280","Text":"We have several types of RNA."},{"Start":"09:31.280 ","End":"09:36.770","Text":"The main RNA that we\u0027ll talk about is the messenger RNA, mRNA."},{"Start":"09:36.770 ","End":"09:38.375","Text":"Well, m stands for messenger,"},{"Start":"09:38.375 ","End":"09:41.610","Text":"it\u0027s the mediator between DNA and proteins."},{"Start":"09:41.610 ","End":"09:44.690","Text":"The mRNA is copied from the DNA and it"},{"Start":"09:44.690 ","End":"09:48.460","Text":"contains information for the construction of proteins."},{"Start":"09:48.460 ","End":"09:51.420","Text":"In order to synthesize the RNA,"},{"Start":"09:51.420 ","End":"09:53.915","Text":"1 of the DNA strands is removed."},{"Start":"09:53.915 ","End":"09:58.370","Text":"Then the RNA is copied using the DNA as a template."},{"Start":"09:58.370 ","End":"10:00.605","Text":"As we said, for each G,"},{"Start":"10:00.605 ","End":"10:04.325","Text":"the RNA gets a C and vice versa."},{"Start":"10:04.325 ","End":"10:08.250","Text":"Instead of a T, we have a U that\u0027s coupled with the A."},{"Start":"10:08.250 ","End":"10:10.300","Text":"The T gets an A, of course,"},{"Start":"10:10.300 ","End":"10:13.380","Text":"and now we have our RNA molecule."},{"Start":"10:13.930 ","End":"10:19.790","Text":"Ribosomes are tiny cellular machines that synthesized proteins."},{"Start":"10:19.790 ","End":"10:23.830","Text":"Ribosomes are made of ribosomal RNA and proteins."},{"Start":"10:23.830 ","End":"10:29.725","Text":"Ribosomal RNA is what we call rRNA where the r stands for ribosomal."},{"Start":"10:29.725 ","End":"10:32.510","Text":"A ribosome has 2 parts,"},{"Start":"10:32.510 ","End":"10:35.285","Text":"a large sub-unit and a small sub-unit."},{"Start":"10:35.285 ","End":"10:39.450","Text":"The mRNAs is fitted in-between the 2 subunits."},{"Start":"10:39.450 ","End":"10:43.115","Text":"Transfer RNA or tRNA,"},{"Start":"10:43.115 ","End":"10:47.960","Text":"carries a single amino acid to the site of protein synthesis on the ribosome."},{"Start":"10:47.960 ","End":"10:50.940","Text":"Here we have the single amino acid."},{"Start":"10:52.670 ","End":"10:56.930","Text":"The tRNA molecule recognizes the codon on the mRNA,"},{"Start":"10:56.930 ","End":"11:01.085","Text":"it binds to it by complimentary base pairing."},{"Start":"11:01.085 ","End":"11:06.805","Text":"The ribosome then adds the amino acid to the growing peptide chain."},{"Start":"11:06.805 ","End":"11:12.230","Text":"Afterwards, the tRNA is disconnected from the mRNA strand."},{"Start":"11:12.230 ","End":"11:16.445","Text":"As the ribosome moves along the mRNA strand,"},{"Start":"11:16.445 ","End":"11:21.150","Text":"more and more amino acids are added to the growing peptide chain."},{"Start":"11:22.100 ","End":"11:25.175","Text":"Eventually we get a polypeptide,"},{"Start":"11:25.175 ","End":"11:27.665","Text":"which is going to be synthesized as a protein."},{"Start":"11:27.665 ","End":"11:31.710","Text":"As the ribosome moves along each strand."},{"Start":"11:32.140 ","End":"11:35.540","Text":"At this point, we can describe the structure of"},{"Start":"11:35.540 ","End":"11:38.885","Text":"nucleic acids and define the 2 types of nucleic acids."},{"Start":"11:38.885 ","End":"11:45.390","Text":"We can explain the structure and role of DNA and explain the structure and roles of RNA."}],"ID":24127},{"Watched":false,"Name":"Exercise 1","Duration":"2m 3s","ChapterTopicVideoID":23290,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.470 ","End":"00:07.510","Text":"A substitution mutation occurs and cytosine is replaced with adenine."},{"Start":"00:07.510 ","End":"00:12.305","Text":"What is the expected impact this will have on the DNA structure?"},{"Start":"00:12.305 ","End":"00:15.700","Text":"Since adenine is larger than cytosine,"},{"Start":"00:15.700 ","End":"00:18.340","Text":"it will not be able to base pair properly with the guanine on"},{"Start":"00:18.340 ","End":"00:21.475","Text":"the opposite strand. Let\u0027s have a look at that."},{"Start":"00:21.475 ","End":"00:25.000","Text":"Here\u0027s 1 strand of DNA and here\u0027s the other strand."},{"Start":"00:25.000 ","End":"00:29.650","Text":"Any DNA nucleotide includes 1 of 4 different bases,"},{"Start":"00:29.650 ","End":"00:35.605","Text":"thymine, guanine, cytosine, or adenine."},{"Start":"00:35.605 ","End":"00:41.440","Text":"The hydrogen bonds that form between the bases and the opposite strands can only occur"},{"Start":"00:41.440 ","End":"00:48.780","Text":"between adenine and thymine or between guanine and cytosine,"},{"Start":"00:48.780 ","End":"00:52.805","Text":"and it doesn\u0027t matter which one is on what side and what strand."},{"Start":"00:52.805 ","End":"00:59.330","Text":"Therefore, when a cytosine in this nucleotide is replaced with adenine,"},{"Start":"01:01.050 ","End":"01:06.590","Text":"adenine and guanine will not form the hydrogen bonds."},{"Start":"01:07.040 ","End":"01:10.440","Text":"This will cause the DNA to bulge."},{"Start":"01:10.440 ","End":"01:15.955","Text":"DNA repair enzymes may recognize this bulge and replace the incorrect nucleotide."},{"Start":"01:15.955 ","End":"01:17.650","Text":"Let\u0027s see how that looks."},{"Start":"01:17.650 ","End":"01:19.840","Text":"We have here the double helix,"},{"Start":"01:19.840 ","End":"01:22.000","Text":"the double strands here."},{"Start":"01:22.000 ","End":"01:26.425","Text":"We said that we\u0027re going to replace 1 of the cytosines,"},{"Start":"01:26.425 ","End":"01:31.379","Text":"let\u0027s take this one for example, with adenine."},{"Start":"01:31.379 ","End":"01:36.050","Text":"Now, the hydrogen bonds that form"},{"Start":"01:36.050 ","End":"01:41.690","Text":"between guanine and cytosine will not form between the adenine and guanine."},{"Start":"01:41.690 ","End":"01:45.565","Text":"What we\u0027ll have here is a bulge in the three-dimensional structure."},{"Start":"01:45.565 ","End":"01:52.280","Text":"DNA repair enzymes are enzymes that run along the strand looking for these bulges."},{"Start":"01:52.280 ","End":"01:56.345","Text":"When they reach here, they can take out the wrong base pair,"},{"Start":"01:56.345 ","End":"02:01.890","Text":"the wrong nucleotide, and replace it with a correct one repairing the DNA."}],"ID":24129},{"Watched":false,"Name":"Exercise 2","Duration":"1m 36s","ChapterTopicVideoID":23291,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.190","Text":"A dehydration reaction leads to formation of a, monomers."},{"Start":"00:05.190 ","End":"00:06.720","Text":"B, water."},{"Start":"00:06.720 ","End":"00:09.240","Text":"C, water and polymers."},{"Start":"00:09.240 ","End":"00:11.355","Text":"Or d, polymer."},{"Start":"00:11.355 ","End":"00:13.875","Text":"What is a dehydration reaction?"},{"Start":"00:13.875 ","End":"00:16.980","Text":"Hydro means water, so dehydration is"},{"Start":"00:16.980 ","End":"00:21.360","Text":"the extraction of water from the molecules participating in this reaction."},{"Start":"00:21.360 ","End":"00:25.700","Text":"Let\u0027s have a look at an example of a dehydration reaction."},{"Start":"00:25.700 ","End":"00:28.880","Text":"Here we see 2 monomers, in this example,"},{"Start":"00:28.880 ","End":"00:34.340","Text":"amino acids that are bonded together by a peptide bond to form a polymer,"},{"Start":"00:34.340 ","End":"00:36.290","Text":"a polypeptide in this example."},{"Start":"00:36.290 ","End":"00:39.350","Text":"And in the process, we have an extraction of"},{"Start":"00:39.350 ","End":"00:42.395","Text":"1 water molecule and this is the dehydration."},{"Start":"00:42.395 ","End":"00:48.380","Text":"The water molecule made of 2 hydrogen atoms and 1 oxygen atom is formed from"},{"Start":"00:48.380 ","End":"00:51.710","Text":"the oxygen and 2 hydrogen atoms from"},{"Start":"00:51.710 ","End":"00:56.030","Text":"the molecules from the monomers participating in this reaction."},{"Start":"00:56.030 ","End":"01:00.650","Text":"Here we have, again, 2 monomers that are connected by"},{"Start":"01:00.650 ","End":"01:06.425","Text":"a peptide bond to form polymer and 1 molecule of water."},{"Start":"01:06.425 ","End":"01:08.765","Text":"Let\u0027s have a look at the answers now."},{"Start":"01:08.765 ","End":"01:10.445","Text":"Monomers, well,"},{"Start":"01:10.445 ","End":"01:14.555","Text":"a dehydration reaction uses monomers but does not form them."},{"Start":"01:14.555 ","End":"01:16.295","Text":"A would be wrong."},{"Start":"01:16.295 ","End":"01:19.184","Text":"The answer is water and polymer."},{"Start":"01:19.184 ","End":"01:21.090","Text":"They\u0027re both right."},{"Start":"01:21.090 ","End":"01:23.510","Text":"The problem is that they\u0027re incomplete since"},{"Start":"01:23.510 ","End":"01:27.935","Text":"the dehydration reaction leads to formation of both a polymer and water."},{"Start":"01:27.935 ","End":"01:29.570","Text":"Therefore, we\u0027re left with answer,"},{"Start":"01:29.570 ","End":"01:31.430","Text":"c, water and polymers."},{"Start":"01:31.430 ","End":"01:33.815","Text":"Here we have our polymer and our water,"},{"Start":"01:33.815 ","End":"01:36.150","Text":"and that is the correct answer."}],"ID":24130},{"Watched":false,"Name":"Exercise 3","Duration":"2m 16s","ChapterTopicVideoID":23292,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.950 ","End":"00:06.270","Text":"The breakdown of polymers involves which of the following reactions?"},{"Start":"00:06.270 ","End":"00:09.750","Text":"A, hydrolysis, B,"},{"Start":"00:09.750 ","End":"00:12.315","Text":"dehydration, C,"},{"Start":"00:12.315 ","End":"00:16.635","Text":"condensation or D, covalent bond."},{"Start":"00:16.635 ","End":"00:19.275","Text":"Let\u0027s have a look at these answers."},{"Start":"00:19.275 ","End":"00:23.295","Text":"Hydrolysis is a word made out of 2 different words."},{"Start":"00:23.295 ","End":"00:28.170","Text":"Hydro meaning water and lysis meaning taking things apart."},{"Start":"00:28.170 ","End":"00:34.455","Text":"This would be a reaction taking things apart using hydro, using water."},{"Start":"00:34.455 ","End":"00:39.225","Text":"Dehydration and condensation processes are actually the same."},{"Start":"00:39.225 ","End":"00:45.815","Text":"In these processes what is involved is a molecule of water is dehydrated"},{"Start":"00:45.815 ","End":"00:49.280","Text":"or condenses from the molecules"},{"Start":"00:49.280 ","End":"00:53.015","Text":"that are involved with the monomers that are involved in the process."},{"Start":"00:53.015 ","End":"00:58.050","Text":"The monomers are dehydrated and the water is condensed."},{"Start":"00:58.100 ","End":"01:00.720","Text":"Answer D, covalent bond."},{"Start":"01:00.720 ","End":"01:04.280","Text":"That just means that 2 atoms are forming a bond with each other."},{"Start":"01:04.280 ","End":"01:06.890","Text":"Here we\u0027re talking about breakdown of polymers."},{"Start":"01:06.890 ","End":"01:09.485","Text":"So this is not relevant at all."},{"Start":"01:09.485 ","End":"01:12.395","Text":"Let\u0027s have a look at an example here."},{"Start":"01:12.395 ","End":"01:14.480","Text":"Here we have a molecule of sucrose,"},{"Start":"01:14.480 ","End":"01:20.160","Text":"which is actually 2 monomers of sugar connected to each other by [inaudible] bond."},{"Start":"01:20.160 ","End":"01:22.270","Text":"Adding 1 water molecule to"},{"Start":"01:22.270 ","End":"01:29.725","Text":"this results in a process of the breakdown of this polymer to 2 monomers"},{"Start":"01:29.725 ","End":"01:34.670","Text":"while the water molecule is taken apart and the oxygen and 1 of the hydrogens"},{"Start":"01:34.670 ","End":"01:40.265","Text":"connects to 1 monomer and the other hydrogen molecule connect to the next monomer."},{"Start":"01:40.265 ","End":"01:45.250","Text":"What we have here is actually taking a bond apart,"},{"Start":"01:45.250 ","End":"01:48.345","Text":"taking 2 monomers apart using water,"},{"Start":"01:48.345 ","End":"01:52.740","Text":"which would be hydro lysis or in 1 word, hydrolysis."},{"Start":"01:52.740 ","End":"01:55.970","Text":"Dehydration and condensation would be the opposite when"},{"Start":"01:55.970 ","End":"01:58.850","Text":"we take the 2 monomers and connect"},{"Start":"01:58.850 ","End":"02:05.745","Text":"them resulting in dehydrating them and condensing 1 molecule of water."},{"Start":"02:05.745 ","End":"02:10.620","Text":"Covalent bond is not relevant and these 2 are the opposite process."},{"Start":"02:10.620 ","End":"02:14.660","Text":"Hydrolysis, taking molecules apart using water,"},{"Start":"02:14.660 ","End":"02:16.860","Text":"is our correct answer."}],"ID":24131},{"Watched":false,"Name":"Exercise 4","Duration":"46s","ChapterTopicVideoID":23293,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.010 ","End":"00:04.695","Text":"Which of these molecules are monosaccharides?"},{"Start":"00:04.695 ","End":"00:09.060","Text":"Fructose, glucose, galactose, and d,"},{"Start":"00:09.060 ","End":"00:10.200","Text":"all of the above."},{"Start":"00:10.200 ","End":"00:13.485","Text":"Let\u0027s have a look at these molecules. Let\u0027s see how they look."},{"Start":"00:13.485 ","End":"00:15.270","Text":"Well, this is the galactose,"},{"Start":"00:15.270 ","End":"00:16.530","Text":"this is the glucose,"},{"Start":"00:16.530 ","End":"00:18.030","Text":"and this is the fructose."},{"Start":"00:18.030 ","End":"00:24.285","Text":"We know that disaccharides would be 2 sugars connected with each other,"},{"Start":"00:24.285 ","End":"00:27.510","Text":"and polysaccharides would be many of these"},{"Start":"00:27.510 ","End":"00:30.684","Text":"connected with each other in chains or branches,"},{"Start":"00:30.684 ","End":"00:34.170","Text":"while monosaccharides are actually single sugars."},{"Start":"00:34.170 ","End":"00:36.614","Text":"Since the galactose, the glucose,"},{"Start":"00:36.614 ","End":"00:39.597","Text":"and fructose all seem to be single sugars,"},{"Start":"00:39.597 ","End":"00:46.510","Text":"you can say that all of the above are monosaccharides. That\u0027s our answer."}],"ID":24132},{"Watched":false,"Name":"Exercise 5","Duration":"57s","ChapterTopicVideoID":23294,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.470 ","End":"00:05.655","Text":"Amylopectin and amylose are: a, monosaccharides;"},{"Start":"00:05.655 ","End":"00:08.340","Text":"b, disaccharides; c,"},{"Start":"00:08.340 ","End":"00:11.145","Text":"lipids; and d, polysaccharides."},{"Start":"00:11.145 ","End":"00:13.050","Text":"Well, let\u0027s have a look at these answers."},{"Start":"00:13.050 ","End":"00:19.010","Text":"Monosaccharides are single sugars which are not connected to each other,"},{"Start":"00:19.010 ","End":"00:23.960","Text":"disaccharides are when we have pairs of these connected to each other,"},{"Start":"00:23.960 ","End":"00:25.775","Text":"lipids are fats,"},{"Start":"00:25.775 ","End":"00:33.065","Text":"and polysaccharides only have long chains of sugars that may be branched or unbranched."},{"Start":"00:33.065 ","End":"00:35.720","Text":"Let\u0027s have a look at these molecules now."},{"Start":"00:35.720 ","End":"00:38.585","Text":"Amylopectin and amylose."},{"Start":"00:38.585 ","End":"00:42.405","Text":"Well, we can see lots of sugar units so we can already"},{"Start":"00:42.405 ","End":"00:45.650","Text":"cross out lipids and we can see that they are not alone,"},{"Start":"00:45.650 ","End":"00:49.085","Text":"monosaccharides, or in pairs like disaccharides."},{"Start":"00:49.085 ","End":"00:52.219","Text":"Rather they\u0027re in long chains, branched or unbranched."},{"Start":"00:52.219 ","End":"00:55.770","Text":"Therefore, our answer would be polysaccharides."}],"ID":24133},{"Watched":false,"Name":"Exercise 6","Duration":"58s","ChapterTopicVideoID":23295,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.460 ","End":"00:06.390","Text":"Which of the following molecules is abundant in plant cell walls?"},{"Start":"00:06.390 ","End":"00:10.635","Text":"A starch, b cellulose,"},{"Start":"00:10.635 ","End":"00:14.744","Text":"c glycogen, and d lactose."},{"Start":"00:14.744 ","End":"00:18.100","Text":"Let\u0027s have a look at these 4 macromolecules."},{"Start":"00:18.100 ","End":"00:22.135","Text":"Starch as we know is found in potatoes."},{"Start":"00:22.135 ","End":"00:27.270","Text":"Plants use starches to store sugar."},{"Start":"00:27.270 ","End":"00:31.230","Text":"Glycogen is the animal equivalent of starch and"},{"Start":"00:31.230 ","End":"00:34.950","Text":"is used by people and animals to store glucose."},{"Start":"00:34.950 ","End":"00:40.710","Text":"Lactose, well anything that has to do with lact we always know it has to do with milk,"},{"Start":"00:40.710 ","End":"00:44.945","Text":"is the disaccharide found in milk."},{"Start":"00:44.945 ","End":"00:47.089","Text":"That leaves us with cellulose,"},{"Start":"00:47.089 ","End":"00:51.440","Text":"which is the molecule that\u0027s most abundant in plant cell walls."},{"Start":"00:51.440 ","End":"00:56.400","Text":"Therefore, the correct answer is b, cellulose."}],"ID":24134},{"Watched":false,"Name":"Exercise 7","Duration":"2m 16s","ChapterTopicVideoID":23296,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.950 ","End":"00:08.460","Text":"Lactose is formed by what bond between glucose and what other sugar."},{"Start":"00:08.460 ","End":"00:14.669","Text":"A: glycosidic bond and the other sugar is, lactose."},{"Start":"00:14.669 ","End":"00:19.645","Text":"B, a glycosidic bond and connection with galactose."},{"Start":"00:19.645 ","End":"00:24.525","Text":"C, a hydrogen bond connecting between glucose and sucrose,"},{"Start":"00:24.525 ","End":"00:30.015","Text":"or D, a hydrogen bond connecting between glucose and fructose."},{"Start":"00:30.015 ","End":"00:34.110","Text":"The word lactose gives us the answer since anything that has"},{"Start":"00:34.110 ","End":"00:37.995","Text":"to do with flact or lactation is something that has to do with milk."},{"Start":"00:37.995 ","End":"00:41.790","Text":"We ending of the word ose tells us it\u0027s a sugar."},{"Start":"00:41.790 ","End":"00:44.675","Text":"We know we\u0027re talking about the disaccharide,"},{"Start":"00:44.675 ","End":"00:47.790","Text":"the double sugar, and milk."},{"Start":"00:47.860 ","End":"00:50.630","Text":"Since we know that the connection between"},{"Start":"00:50.630 ","End":"00:55.115","Text":"monosaccharides to make disaccharides is called a glycosidic bond."},{"Start":"00:55.115 ","End":"00:59.990","Text":"We can really cross out answers C and D. I\u0027m talking about hydrogen bonds."},{"Start":"00:59.990 ","End":"01:03.455","Text":"The correct bond is a glycosidic bond."},{"Start":"01:03.455 ","End":"01:06.950","Text":"Now, lactose is double bond,"},{"Start":"01:06.950 ","End":"01:15.020","Text":"we know that one of these sugars from the question is the glucose and the question is,"},{"Start":"01:15.020 ","End":"01:16.540","Text":"what is the other sugar?"},{"Start":"01:16.540 ","End":"01:19.955","Text":"Is it lactose or is it galactose?"},{"Start":"01:19.955 ","End":"01:23.750","Text":"Since the question is about lactose being formed by 2 sugars,"},{"Start":"01:23.750 ","End":"01:27.140","Text":"we can cross out lactose being the end of lactose."},{"Start":"01:27.140 ","End":"01:30.950","Text":"Therefore the correct answer would be that lactose is formed by"},{"Start":"01:30.950 ","End":"01:36.725","Text":"a glycosidic bond between glucose and galactose. This is the answer."},{"Start":"01:36.725 ","End":"01:44.425","Text":"Galactose. Let\u0027s have a look at the process."},{"Start":"01:44.425 ","End":"01:47.265","Text":"Here we have galactose monomer,"},{"Start":"01:47.265 ","End":"01:53.030","Text":"and glucose monomer connecting each other to make a disaccharide a polymer."},{"Start":"01:53.030 ","End":"01:56.765","Text":"We have here dehydration of a water molecule"},{"Start":"01:56.765 ","End":"02:00.905","Text":"coming from the 2 monomers making the lactose."},{"Start":"02:00.905 ","End":"02:05.000","Text":"The lactose is in fact made by galactose and"},{"Start":"02:05.000 ","End":"02:09.905","Text":"glucose connected by a glycosidic bond and a correct answer would be B,"},{"Start":"02:09.905 ","End":"02:14.850","Text":"lactose is formed by a glycosidic bond between glucose and galactose."}],"ID":24135},{"Watched":false,"Name":"Exercise 8","Duration":"1m 45s","ChapterTopicVideoID":23297,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.100 ","End":"00:06.645","Text":"Which of the following characteristics is not present in saturated fat?"},{"Start":"00:06.645 ","End":"00:11.010","Text":"Notice that we\u0027re asked to find the one that is not present in saturated fat."},{"Start":"00:11.010 ","End":"00:15.540","Text":"A, at room temperature they\u0027re solid; b,"},{"Start":"00:15.540 ","End":"00:20.105","Text":"saturated fats have single bonds within the carbon chain; c,"},{"Start":"00:20.105 ","End":"00:22.823","Text":"they\u0027re usually obtained from animal sources;"},{"Start":"00:22.823 ","End":"00:26.445","Text":"and d, they tend to dissolve in water easily."},{"Start":"00:26.445 ","End":"00:29.345","Text":"Let\u0027s have a look at saturated fats."},{"Start":"00:29.345 ","End":"00:31.595","Text":"We know that in saturated fats,"},{"Start":"00:31.595 ","End":"00:37.370","Text":"all the carbon atoms along the chain have double connections to hydrogen."},{"Start":"00:37.370 ","End":"00:39.970","Text":"Therefore, they have single bonds between each other,"},{"Start":"00:39.970 ","End":"00:42.890","Text":"unlike unsaturated fatty acids that along"},{"Start":"00:42.890 ","End":"00:46.190","Text":"the chain we find carbons that are missing this hydrogen."},{"Start":"00:46.190 ","End":"00:48.860","Text":"Therefore, they form double bonds and they"},{"Start":"00:48.860 ","End":"00:53.660","Text":"form angles that make them less solid at room temperature."},{"Start":"00:53.660 ","End":"00:57.860","Text":"But saturated fatty acids only have these single bonds."},{"Start":"00:57.860 ","End":"01:00.350","Text":"Therefore, they are also solid at room temperature,"},{"Start":"01:00.350 ","End":"01:02.150","Text":"like there\u0027s butter over here."},{"Start":"01:02.150 ","End":"01:05.540","Text":"This is true and this is true."},{"Start":"01:05.540 ","End":"01:07.070","Text":"As a rule of thumb,"},{"Start":"01:07.070 ","End":"01:09.620","Text":"saturated fatty acids are obtained from"},{"Start":"01:09.620 ","End":"01:14.195","Text":"animal sources like this butter or lard or other fats from animals."},{"Start":"01:14.195 ","End":"01:16.760","Text":"While unsaturated fatty acids like olive oil,"},{"Start":"01:16.760 ","End":"01:19.220","Text":"for example, are obtained from plant sources."},{"Start":"01:19.220 ","End":"01:21.395","Text":"Therefore, c is also correct."},{"Start":"01:21.395 ","End":"01:23.000","Text":"Let\u0027s have a look at d,"},{"Start":"01:23.000 ","End":"01:24.935","Text":"they tend to dissolve in water easily."},{"Start":"01:24.935 ","End":"01:27.290","Text":"Well, generally, we know that fatty acids"},{"Start":"01:27.290 ","End":"01:29.825","Text":"don\u0027t dissolve in water as they\u0027re hydrophobic,"},{"Start":"01:29.825 ","End":"01:33.035","Text":"whether they\u0027re saturated or unsaturated."},{"Start":"01:33.035 ","End":"01:38.150","Text":"Since we\u0027re looking for the characteristic that\u0027s not present in saturated fat,"},{"Start":"01:38.150 ","End":"01:40.280","Text":"therefore, the correct answer is d,"},{"Start":"01:40.280 ","End":"01:42.185","Text":"since it\u0027s not present in saturated fat,"},{"Start":"01:42.185 ","End":"01:44.280","Text":"or other fats either."}],"ID":24136},{"Watched":false,"Name":"Exercise 9","Duration":"2m 4s","ChapterTopicVideoID":23268,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.620 ","End":"00:03.720","Text":"Phospholipids are components of,"},{"Start":"00:03.720 ","End":"00:07.299","Text":"a, animal cells plasma membrane."},{"Start":"00:07.299 ","End":"00:09.900","Text":"B, the ring structure of steroids."},{"Start":"00:09.900 ","End":"00:12.540","Text":"C, DNA and RNA."},{"Start":"00:12.540 ","End":"00:15.975","Text":"Or d, polymeric hydrocarbon chains."},{"Start":"00:15.975 ","End":"00:18.870","Text":"Let\u0027s have a look at these answers 1 by 1."},{"Start":"00:18.870 ","End":"00:22.830","Text":"We\u0027ll start by looking at the plasma membrane of cells."},{"Start":"00:22.830 ","End":"00:26.325","Text":"Here we have a cell, this is the inner part of the cell,"},{"Start":"00:26.325 ","End":"00:28.785","Text":"and we have here the membranes surrounding it."},{"Start":"00:28.785 ","End":"00:30.600","Text":"We have a closer look at the membrane,"},{"Start":"00:30.600 ","End":"00:32.610","Text":"we can see it had a bi-layer,"},{"Start":"00:32.610 ","End":"00:35.235","Text":"a double layer of these macromolecules."},{"Start":"00:35.235 ","End":"00:38.655","Text":"This macromolecule is actually a phospholipid."},{"Start":"00:38.655 ","End":"00:45.110","Text":"A phospholipid has a hydrophilic head meaning water loving head and hydrophobic tails,"},{"Start":"00:45.110 ","End":"00:47.825","Text":"tails that keep away from water."},{"Start":"00:47.825 ","End":"00:49.970","Text":"The hydrophilic head,"},{"Start":"00:49.970 ","End":"00:54.289","Text":"the water-loving head faces both inwards and outwards,"},{"Start":"00:54.289 ","End":"00:57.680","Text":"where there\u0027s an environment which is watery."},{"Start":"00:57.680 ","End":"01:01.745","Text":"In-between the bi-layer we have the hydrophobic tails."},{"Start":"01:01.745 ","End":"01:07.310","Text":"This is a very stable since the hydrophobic tails will not be able to mix with the water."},{"Start":"01:07.310 ","End":"01:11.773","Text":"Therefore, the correct answer is in fact animal cells plasma membrane,"},{"Start":"01:11.773 ","End":"01:16.835","Text":"but note that this answer would be true for any cells not just animal cells."},{"Start":"01:16.835 ","End":"01:19.010","Text":"Let\u0027s just have a look at the other answers"},{"Start":"01:19.010 ","End":"01:21.415","Text":"and make sure that we\u0027re not missing out on anything."},{"Start":"01:21.415 ","End":"01:24.600","Text":"B, the ring structure of steroids."},{"Start":"01:24.600 ","End":"01:31.285","Text":"Steroids are in fact many connected rings but there are no phospholipids here."},{"Start":"01:31.285 ","End":"01:33.860","Text":"C, DNA and RNA."},{"Start":"01:33.860 ","End":"01:36.865","Text":"Here we have nucleotide,"},{"Start":"01:36.865 ","End":"01:38.760","Text":"no phospholipids at all."},{"Start":"01:38.760 ","End":"01:40.310","Text":"We have a phosphate group,"},{"Start":"01:40.310 ","End":"01:42.305","Text":"a sugar group, and a base."},{"Start":"01:42.305 ","End":"01:47.255","Text":"C would also not be correct or the polymeric hydrocarbon chains."},{"Start":"01:47.255 ","End":"01:49.140","Text":"Let\u0027s see an example of those,"},{"Start":"01:49.140 ","End":"01:52.400","Text":"we have here some fatty acids saturated or unsaturated."},{"Start":"01:52.400 ","End":"01:54.965","Text":"Again, there are no phospholipids here at all,"},{"Start":"01:54.965 ","End":"01:58.620","Text":"and therefore backtrack correct answer which is a."},{"Start":"01:58.620 ","End":"02:03.990","Text":"Phospholipids are in fact components of animal cell plasma membranes."}],"ID":24107},{"Watched":false,"Name":"Exercise 10","Duration":"1m 54s","ChapterTopicVideoID":23269,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:02.180 ","End":"00:05.055","Text":"When water and oil are mixed,"},{"Start":"00:05.055 ","End":"00:08.355","Text":"oil separates from the water because oils are,"},{"Start":"00:08.355 ","End":"00:10.470","Text":"a, hydrophobic."},{"Start":"00:10.470 ","End":"00:12.480","Text":"B, hydrophilic."},{"Start":"00:12.480 ","End":"00:15.135","Text":"C, lipids. D,"},{"Start":"00:15.135 ","End":"00:21.360","Text":"both a and c. Let\u0027s have a look at the answers."},{"Start":"00:21.360 ","End":"00:23.310","Text":"Hydrophobic."},{"Start":"00:23.310 ","End":"00:28.215","Text":"Hydrophobic means when something tends to repel or fails to mix with water."},{"Start":"00:28.215 ","End":"00:30.240","Text":"It\u0027s made up of 2 words, hydro,"},{"Start":"00:30.240 ","End":"00:32.970","Text":"which means water and phobic which means at"},{"Start":"00:32.970 ","End":"00:37.230","Text":"phobia when 1 has an extreme aversion from something."},{"Start":"00:37.230 ","End":"00:41.980","Text":"That is true, oils are hydrophobic and they don\u0027t mix well with water."},{"Start":"00:41.980 ","End":"00:45.290","Text":"B, hydrophilic, which is the exact opposite."},{"Start":"00:45.290 ","End":"00:48.230","Text":"Hydro is water and philic means a loving of."},{"Start":"00:48.230 ","End":"00:50.465","Text":"Since oils are not hydrophilic,"},{"Start":"00:50.465 ","End":"00:52.460","Text":"this would be a wrong answer."},{"Start":"00:52.460 ","End":"00:57.605","Text":"C, oil and water don\u0027t mix because oils are lipids. That is true."},{"Start":"00:57.605 ","End":"01:00.920","Text":"Oils are lipids, but that\u0027s not the reason that they don\u0027t mix well"},{"Start":"01:00.920 ","End":"01:04.610","Text":"with water because of their name is because they\u0027re hydrophobic."},{"Start":"01:04.610 ","End":"01:08.725","Text":"Therefore also a and c are wrong and since we know that c is wrong."},{"Start":"01:08.725 ","End":"01:11.270","Text":"Why are oil is hydrophobic?"},{"Start":"01:11.270 ","End":"01:15.365","Text":"Let\u0027s have a look at the molecules here we have the macromolecules of"},{"Start":"01:15.365 ","End":"01:20.749","Text":"fatty acids as an example for oils and we have here the water molecules."},{"Start":"01:20.749 ","End":"01:24.495","Text":"In the water molecule, the covalent bonds are polar."},{"Start":"01:24.495 ","End":"01:27.620","Text":"Meaning that the oxygen atom attracts"},{"Start":"01:27.620 ","End":"01:32.285","Text":"the negatively charged electrons stronger than the hydrogen atoms do."},{"Start":"01:32.285 ","End":"01:36.220","Text":"Therefore we find a negative charge"},{"Start":"01:36.850 ","End":"01:42.229","Text":"towards this side and a positive charge towards this side of the water molecules."},{"Start":"01:42.229 ","End":"01:44.600","Text":"On the other hand, the fatty acids have"},{"Start":"01:44.600 ","End":"01:47.675","Text":"no such polar connections and"},{"Start":"01:47.675 ","End":"01:51.380","Text":"therefore they are not polar at all and they will not mix well with water."},{"Start":"01:51.380 ","End":"01:53.970","Text":"They are hydrophobic."}],"ID":24108},{"Watched":false,"Name":"Exercise 11","Duration":"2m 45s","ChapterTopicVideoID":23270,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.500 ","End":"00:07.789","Text":"The process which converts unsaturated fatty acids into saturated fatty acids is A,"},{"Start":"00:07.789 ","End":"00:11.280","Text":"hydration, B, dehydration,"},{"Start":"00:11.280 ","End":"00:17.100","Text":"C, dehydrogenation or D, hydrogenation."},{"Start":"00:17.100 ","End":"00:22.190","Text":"Let\u0027s have a look at this question and try to understand better what we\u0027re asked about."},{"Start":"00:22.190 ","End":"00:27.260","Text":"We want to convert unsaturated fatty acids, what are unsaturated fatty acids?"},{"Start":"00:27.260 ","End":"00:31.235","Text":"These are oils made from plants: the olive oil,"},{"Start":"00:31.235 ","End":"00:33.155","Text":"corn oil, or anything else,"},{"Start":"00:33.155 ","End":"00:36.410","Text":"into saturated fatty acids such as margarine."},{"Start":"00:36.410 ","End":"00:38.090","Text":"How would we do that?"},{"Start":"00:38.090 ","End":"00:40.640","Text":"Let\u0027s have a look at the molecules."},{"Start":"00:40.640 ","End":"00:47.120","Text":"We start with unsaturated fatty acids and we want to get saturated fatty acids."},{"Start":"00:47.120 ","End":"00:48.770","Text":"What\u0027s the difference between them?"},{"Start":"00:48.770 ","End":"00:52.640","Text":"The difference is that in the unsaturated fatty acids,"},{"Start":"00:52.640 ","End":"00:55.745","Text":"the chains of carbons has an angle."},{"Start":"00:55.745 ","End":"00:58.345","Text":"Why does it have this angle?"},{"Start":"00:58.345 ","End":"01:01.715","Text":"The reason is that some of the carbon atoms"},{"Start":"01:01.715 ","End":"01:05.420","Text":"don\u0027t have 2 connections to hydrogens, but only 1."},{"Start":"01:05.420 ","End":"01:08.840","Text":"That leaves an extra electron for a double covalent bond."},{"Start":"01:08.840 ","End":"01:13.820","Text":"This double covalent bond is what gives the unsaturated fatty acids these angles,"},{"Start":"01:13.820 ","End":"01:17.950","Text":"and therefore they\u0027re less easily densely packed."},{"Start":"01:17.950 ","End":"01:21.830","Text":"On the other hand, unsaturated fatty acids,"},{"Start":"01:21.830 ","End":"01:26.615","Text":"all the carbon atoms are connected with 2 hydrogen atoms."},{"Start":"01:26.615 ","End":"01:29.135","Text":"Therefore, they have no electrons"},{"Start":"01:29.135 ","End":"01:32.810","Text":"free to make a double bond with the next carbon in the chain."},{"Start":"01:32.810 ","End":"01:38.210","Text":"That is why they\u0027re straight and they can pack densely very easily."},{"Start":"01:38.210 ","End":"01:42.755","Text":"For that reason, in room temperature, oils are liquid,"},{"Start":"01:42.755 ","End":"01:47.705","Text":"while margarine and other saturated fatty acids are solid."},{"Start":"01:47.705 ","End":"01:52.235","Text":"What do we need to do to change this molecule into this molecule?"},{"Start":"01:52.235 ","End":"01:55.950","Text":"What we need to do is to add hydrogen atoms,"},{"Start":"01:57.400 ","End":"01:59.960","Text":"then lose the double bond,"},{"Start":"01:59.960 ","End":"02:03.505","Text":"and turn this micro molecule to be straight."},{"Start":"02:03.505 ","End":"02:07.445","Text":"Let\u0027s see our answers, hydration, hydro means water."},{"Start":"02:07.445 ","End":"02:08.945","Text":"We don\u0027t need to add water."},{"Start":"02:08.945 ","End":"02:11.990","Text":"Dehydration, that means taking away water."},{"Start":"02:11.990 ","End":"02:14.405","Text":"We don\u0027t need to take away water molecules either."},{"Start":"02:14.405 ","End":"02:17.120","Text":"Hydration and dehydration are both wrong."},{"Start":"02:17.120 ","End":"02:20.985","Text":"Let\u0027s see c and d. Dehydrogenation,"},{"Start":"02:20.985 ","End":"02:24.380","Text":"here we have the word hydrogen and d"},{"Start":"02:24.380 ","End":"02:29.150","Text":"means take it away so we don\u0027t need to take away any of the hydrogen here."},{"Start":"02:29.150 ","End":"02:31.220","Text":"On the contrary, we need to add them."},{"Start":"02:31.220 ","End":"02:34.340","Text":"The correct answer would be hydrogenation."},{"Start":"02:34.340 ","End":"02:37.010","Text":"Adding the hydrogen atoms to this molecule to"},{"Start":"02:37.010 ","End":"02:40.220","Text":"strain it out and get saturated fatty acids."},{"Start":"02:40.220 ","End":"02:44.700","Text":"The correct answer is D, hydrogenation."}],"ID":24109},{"Watched":false,"Name":"Exercise 12","Duration":"1m 40s","ChapterTopicVideoID":23271,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.470 ","End":"00:03.420","Text":"The molecule at the right is a;"},{"Start":"00:03.420 ","End":"00:05.805","Text":"A, carbohydrate, B,"},{"Start":"00:05.805 ","End":"00:11.055","Text":"protein, C, DNA, or D, an amino acid?"},{"Start":"00:11.055 ","End":"00:13.560","Text":"Let\u0027s have a look at these answers."},{"Start":"00:13.560 ","End":"00:16.200","Text":"What\u0027s the structure of a carbohydrate?"},{"Start":"00:16.200 ","End":"00:21.300","Text":"Carbohydrates are made out of carbon chains which can also turn be rings."},{"Start":"00:21.300 ","End":"00:24.900","Text":"They can be single or they can be double."},{"Start":"00:24.900 ","End":"00:28.515","Text":"Or they can be long chains with branches."},{"Start":"00:28.515 ","End":"00:30.420","Text":"This is not the case here,"},{"Start":"00:30.420 ","End":"00:33.315","Text":"and therefore carbohydrate is wrong,"},{"Start":"00:33.315 ","End":"00:37.440","Text":"right here, A. B protein."},{"Start":"00:37.440 ","End":"00:39.375","Text":"What do we know about proteins?"},{"Start":"00:39.375 ","End":"00:41.720","Text":"The protein is a large macromolecule."},{"Start":"00:41.720 ","End":"00:43.370","Text":"It\u0027s a very complex structure."},{"Start":"00:43.370 ","End":"00:47.615","Text":"You including alpha helixes and beta-pleated sheets."},{"Start":"00:47.615 ","End":"00:50.075","Text":"This is certainly not the case here."},{"Start":"00:50.075 ","End":"00:52.835","Text":"Protein is also not an option."},{"Start":"00:52.835 ","End":"00:56.850","Text":"The structure of DNA is a double helix."},{"Start":"00:56.950 ","End":"00:59.360","Text":"This is not what\u0027s happening here at all."},{"Start":"00:59.360 ","End":"01:01.925","Text":"Again, a long macromolecule."},{"Start":"01:01.925 ","End":"01:04.880","Text":"We can cross out DNA."},{"Start":"01:04.880 ","End":"01:07.100","Text":"D, the amino acid."},{"Start":"01:07.100 ","End":"01:08.495","Text":"That is the correct answer."},{"Start":"01:08.495 ","End":"01:13.490","Text":"This in fact is an amino acid and we can see here the 3 different parts of it."},{"Start":"01:13.490 ","End":"01:18.605","Text":"This is the carboxyl group."},{"Start":"01:18.605 ","End":"01:26.185","Text":"This here is the amino group."},{"Start":"01:26.185 ","End":"01:28.470","Text":"Here we have R,"},{"Start":"01:28.470 ","End":"01:32.730","Text":"the abbreviation for the long side chain."},{"Start":"01:35.710 ","End":"01:40.810","Text":"Therefore, the correct answer is D, amino acid."}],"ID":24110},{"Watched":false,"Name":"Exercise 13","Duration":"1m 14s","ChapterTopicVideoID":23272,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.805","Text":"The monomer unit of protein is;"},{"Start":"00:02.805 ","End":"00:05.805","Text":"A, nucleotides, B,"},{"Start":"00:05.805 ","End":"00:08.400","Text":"disaccharides, C,"},{"Start":"00:08.400 ","End":"00:13.240","Text":"amino acids, or D, tRNA."},{"Start":"00:13.550 ","End":"00:16.185","Text":"Let\u0027s have a look at these answers."},{"Start":"00:16.185 ","End":"00:17.820","Text":"What are nucleotides?"},{"Start":"00:17.820 ","End":"00:21.794","Text":"These are in fact monomers of a macromolecule but not of proteins,"},{"Start":"00:21.794 ","End":"00:23.774","Text":"rather DNA or RNA,"},{"Start":"00:23.774 ","End":"00:25.875","Text":"which are nucleic acids."},{"Start":"00:25.875 ","End":"00:30.090","Text":"Disaccharides, di means double and saccharides are sugars,"},{"Start":"00:30.090 ","End":"00:34.720","Text":"and we have here the double sugars such as lactose found in milk."},{"Start":"00:34.720 ","End":"00:37.805","Text":"Again, it\u0027s not a monomer of protein."},{"Start":"00:37.805 ","End":"00:39.950","Text":"We can erase A and B."},{"Start":"00:39.950 ","End":"00:41.450","Text":"C, amino acids,"},{"Start":"00:41.450 ","End":"00:43.450","Text":"we\u0027ll keep that as an option."},{"Start":"00:43.450 ","End":"00:46.515","Text":"Let\u0027s look at answer D, tRNA."},{"Start":"00:46.515 ","End":"00:50.255","Text":"Well, tRNA is in fact involved in protein synthesis,"},{"Start":"00:50.255 ","End":"00:51.935","Text":"but it is not the monomer,"},{"Start":"00:51.935 ","End":"00:53.810","Text":"rather what carries the monomer,"},{"Start":"00:53.810 ","End":"00:55.070","Text":"which is amino acids."},{"Start":"00:55.070 ","End":"00:58.870","Text":"Let\u0027s have a close look at the structure of the protein."},{"Start":"00:58.870 ","End":"01:00.410","Text":"We have here the secondary structure,"},{"Start":"01:00.410 ","End":"01:03.500","Text":"the Beta-pleated sheets and the Alpha helices."},{"Start":"01:03.500 ","End":"01:05.270","Text":"But if you look at the primary structure,"},{"Start":"01:05.270 ","End":"01:09.455","Text":"we\u0027ll see that the protein is actually a long chain of amino acids."},{"Start":"01:09.455 ","End":"01:14.130","Text":"Therefore, our correct answer is C, amino acids."}],"ID":24111},{"Watched":false,"Name":"Exercise 14","Duration":"1m 52s","ChapterTopicVideoID":23273,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.080 ","End":"00:08.550","Text":"There are how many common amino acids which differ from each other by what group?"},{"Start":"00:08.550 ","End":"00:14.700","Text":"A, 20 common amino acids different from each other by the number of carbons."},{"Start":"00:14.700 ","End":"00:19.290","Text":"B, 20 common amino acids different by the amino group."},{"Start":"00:19.290 ","End":"00:23.760","Text":"C, 21 amino acids different by the carboxylic group."},{"Start":"00:23.760 ","End":"00:27.660","Text":"D, 20 amino acids different by the R group."},{"Start":"00:27.660 ","End":"00:34.000","Text":"Or e, 25 amino acids different by the length of the amino acid."},{"Start":"00:34.000 ","End":"00:36.510","Text":"Let\u0027s have a look at amino acids."},{"Start":"00:36.510 ","End":"00:41.325","Text":"Any common table will show us that there are 20 different common amino acids."},{"Start":"00:41.325 ","End":"00:45.835","Text":"Therefore, we can cross out the answers with 25 and 21."},{"Start":"00:45.835 ","End":"00:50.240","Text":"The second part of the question is how these amino acids differ from each other."},{"Start":"00:50.240 ","End":"00:53.885","Text":"By what group? Number of carbons or the amino group,"},{"Start":"00:53.885 ","End":"00:55.940","Text":"or the R group?"},{"Start":"00:55.940 ","End":"01:02.630","Text":"Let\u0027s have a look. The amino acids structure shows us there\u0027s an amino group."},{"Start":"01:02.630 ","End":"01:05.900","Text":"Here we have it. It\u0027s the same in all of them."},{"Start":"01:05.900 ","End":"01:10.760","Text":"This is wrong. We also have a carboxyl group,"},{"Start":"01:10.760 ","End":"01:13.880","Text":"which is the same in all of the acids."},{"Start":"01:13.880 ","End":"01:17.840","Text":"We can also erase this one."},{"Start":"01:17.840 ","End":"01:23.555","Text":"What we\u0027re left is the number of carbons and the R group."},{"Start":"01:23.555 ","End":"01:26.340","Text":"Let\u0027s have a closer look at the structure."},{"Start":"01:26.380 ","End":"01:29.450","Text":"We have the amino group, the carboxyl group,"},{"Start":"01:29.450 ","End":"01:31.715","Text":"and the R group, the side chain,"},{"Start":"01:31.715 ","End":"01:34.610","Text":"which is in fact different here we can see we have rings"},{"Start":"01:34.610 ","End":"01:37.190","Text":"and we have short and long all kinds of other structures here."},{"Start":"01:37.190 ","End":"01:39.200","Text":"All these are the R groups."},{"Start":"01:39.200 ","End":"01:43.355","Text":"This is what makes the difference between the different amino acids."},{"Start":"01:43.355 ","End":"01:46.430","Text":"The correct answer is D. There are"},{"Start":"01:46.430 ","End":"01:52.680","Text":"20 common amino acids which differ from each other by the R group or the side chain."}],"ID":24112},{"Watched":false,"Name":"Exercise 15","Duration":"1m 10s","ChapterTopicVideoID":23274,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.758","Text":"Alpha helix and Beta-pleated sheet are part of what protein structure?"},{"Start":"00:06.758 ","End":"00:09.195","Text":"A, primary, b,"},{"Start":"00:09.195 ","End":"00:11.235","Text":"secondary, c,"},{"Start":"00:11.235 ","End":"00:15.000","Text":"tertiary, or d, quaternary."},{"Start":"00:15.000 ","End":"00:17.700","Text":"Well, what are all these structures?"},{"Start":"00:17.700 ","End":"00:22.905","Text":"The primary structure of a protein is the linear sequence of amino acids."},{"Start":"00:22.905 ","End":"00:25.560","Text":"The secondary structure here,"},{"Start":"00:25.560 ","End":"00:28.140","Text":"is the regular structure of proteins formed by"},{"Start":"00:28.140 ","End":"00:33.230","Text":"intramolecular hydrogen bonding between atoms of the different amino acids,"},{"Start":"00:33.230 ","End":"00:35.450","Text":"forming Alpha helix structure,"},{"Start":"00:35.450 ","End":"00:39.545","Text":"like we can see here, or a beta-pleated sheets like we can see here."},{"Start":"00:39.545 ","End":"00:44.900","Text":"The tertiary structure is the three-dimensional confirmation of a protein."},{"Start":"00:44.900 ","End":"00:47.330","Text":"And the quaternary structure is"},{"Start":"00:47.330 ","End":"00:50.480","Text":"the association of different polypeptides with each other,"},{"Start":"00:50.480 ","End":"00:54.440","Text":"each of them in effect a sub-unit of 1 larger protein."},{"Start":"00:54.440 ","End":"00:57.980","Text":"The correct answer is the secondary structure,"},{"Start":"00:57.980 ","End":"01:03.245","Text":"which is the structure of proteins formed by the intramolecular hydrogen bonds between"},{"Start":"01:03.245 ","End":"01:10.050","Text":"the different amino acids forming the Beta-pleated sheet or the Alpha helix shapes."}],"ID":24113},{"Watched":false,"Name":"Exercise 16","Duration":"1m 48s","ChapterTopicVideoID":23275,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.290 ","End":"00:04.500","Text":"A nucleotide of RNA may contain: a,"},{"Start":"00:04.500 ","End":"00:06.660","Text":"ribose, uracil,"},{"Start":"00:06.660 ","End":"00:08.445","Text":"and a phosphate group."},{"Start":"00:08.445 ","End":"00:12.660","Text":"B, deoxyribose, uracil, and a phosphate group."},{"Start":"00:12.660 ","End":"00:16.845","Text":"C, deoxyribose, thymine, and a phosphate group."},{"Start":"00:16.845 ","End":"00:18.765","Text":"Or d, ribose,"},{"Start":"00:18.765 ","End":"00:20.760","Text":"thiamine, and a phosphate group."},{"Start":"00:20.760 ","End":"00:22.590","Text":"In order to answer this question,"},{"Start":"00:22.590 ","End":"00:26.350","Text":"let\u0027s have a close look at what nucleotides contain."},{"Start":"00:26.450 ","End":"00:30.200","Text":"Here\u0027s a nucleotide because it has a base,"},{"Start":"00:30.200 ","End":"00:32.765","Text":"a sugar, and a phosphate group."},{"Start":"00:32.765 ","End":"00:36.575","Text":"Phosphate group would be correct in all the answers."},{"Start":"00:36.575 ","End":"00:40.085","Text":"Now let\u0027s have a look at the sugars."},{"Start":"00:40.085 ","End":"00:45.785","Text":"The sugar can either be a ribose in RNA or deoxyribose in DNA."},{"Start":"00:45.785 ","End":"00:49.220","Text":"The difference between the ribose and deoxyribose is"},{"Start":"00:49.220 ","End":"00:52.940","Text":"that the deoxyribose is missing its oxygen here."},{"Start":"00:52.940 ","End":"00:57.680","Text":"Therefore, the correct answer is it must have ribose and not deoxyribose,"},{"Start":"00:57.680 ","End":"01:01.235","Text":"since the question is about nucleotide of RNA."},{"Start":"01:01.235 ","End":"01:03.985","Text":"Now let\u0027s have a look at the bases."},{"Start":"01:03.985 ","End":"01:08.955","Text":"There are 2 groups of bases, purines and pyrimidines."},{"Start":"01:08.955 ","End":"01:11.555","Text":"The purines A or G,"},{"Start":"01:11.555 ","End":"01:15.530","Text":"adenine and guanine, are not different between DNA and RNA."},{"Start":"01:15.530 ","End":"01:17.750","Text":"But in the group of pyrimidines,"},{"Start":"01:17.750 ","End":"01:20.120","Text":"we have common cytosine in both of them,"},{"Start":"01:20.120 ","End":"01:26.880","Text":"but thymine only appears in DNA and uracil only appears in RNA."},{"Start":"01:27.440 ","End":"01:31.065","Text":"We can now take off answer d with thiamine,"},{"Start":"01:31.065 ","End":"01:35.405","Text":"and we know that a nucleotide of RNA may contain ribose,"},{"Start":"01:35.405 ","End":"01:37.775","Text":"uracil, and a phosphate group."},{"Start":"01:37.775 ","End":"01:41.765","Text":"While ribose and phosphate group will for sure appear in the RNA nucleotide,"},{"Start":"01:41.765 ","End":"01:44.525","Text":"uracil may be changed with different bases,"},{"Start":"01:44.525 ","End":"01:48.660","Text":"such as cytosine, adenine, or guanine."}],"ID":24114},{"Watched":false,"Name":"Exercise 17","Duration":"50s","ChapterTopicVideoID":23276,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.800 ","End":"00:05.625","Text":"The building blocks of nucleic acids are A, phosphates."},{"Start":"00:05.625 ","End":"00:08.070","Text":"B, nitrogenous bases."},{"Start":"00:08.070 ","End":"00:10.170","Text":"C, amino acids."},{"Start":"00:10.170 ","End":"00:12.810","Text":"Or d, nucleotides."},{"Start":"00:12.810 ","End":"00:19.185","Text":"Well, phosphates in nitrogenous bases both are the building blocks of nucleotides,"},{"Start":"00:19.185 ","End":"00:22.690","Text":"while amino acids build proteins."},{"Start":"00:25.910 ","End":"00:29.790","Text":"Therefore, the correct answer would be nucleotides."},{"Start":"00:29.790 ","End":"00:32.415","Text":"Let\u0027s have a quick look at a nucleic acid here."},{"Start":"00:32.415 ","End":"00:34.665","Text":"We have a chain of nucleic acids."},{"Start":"00:34.665 ","End":"00:38.185","Text":"The building blocks are these nucleotides here, see?"},{"Start":"00:38.185 ","End":"00:41.525","Text":"Each nucleotide is made of a phosphate group,"},{"Start":"00:41.525 ","End":"00:44.986","Text":"a nitrogenous base, and a sugar."},{"Start":"00:44.986 ","End":"00:50.010","Text":"The correct answer is in fact, D, nucleotides."}],"ID":24115},{"Watched":false,"Name":"Exercise 18","Duration":"1m 23s","ChapterTopicVideoID":23277,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.619","Text":"The 4 major biological macromolecules include: A,"},{"Start":"00:04.619 ","End":"00:08.480","Text":"carbohydrates, saccharides, lipids,"},{"Start":"00:08.480 ","End":"00:10.415","Text":"and proteins; B,"},{"Start":"00:10.415 ","End":"00:13.430","Text":"carbohydrates, lipids, proteins,"},{"Start":"00:13.430 ","End":"00:15.640","Text":"and amino acids; C,"},{"Start":"00:15.640 ","End":"00:18.660","Text":"carbohydrates, lipids, proteins,"},{"Start":"00:18.660 ","End":"00:20.370","Text":"and nucleic acids;"},{"Start":"00:20.370 ","End":"00:22.380","Text":"D, none of the above."},{"Start":"00:22.380 ","End":"00:24.135","Text":"Let\u0027s have a look at these answers."},{"Start":"00:24.135 ","End":"00:28.095","Text":"A, carbohydrates, that\u0027s correct."},{"Start":"00:28.095 ","End":"00:31.860","Text":"Saccharides; carbohydrates are made of saccharides."},{"Start":"00:31.860 ","End":"00:33.630","Text":"These are the building blocks of them,"},{"Start":"00:33.630 ","End":"00:34.980","Text":"so this incorrect,"},{"Start":"00:34.980 ","End":"00:37.125","Text":"and we can already go on to the next answer."},{"Start":"00:37.125 ","End":"00:38.940","Text":"Carbohydrates is correct;"},{"Start":"00:38.940 ","End":"00:41.250","Text":"lipids, these are all the fats and oils, yeah;"},{"Start":"00:41.250 ","End":"00:43.055","Text":"proteins, that works;"},{"Start":"00:43.055 ","End":"00:46.745","Text":"amino acids are the building blocks of proteins."},{"Start":"00:46.745 ","End":"00:49.600","Text":"They are certainly not macromolecules; they\u0027re quite small."},{"Start":"00:49.600 ","End":"00:51.980","Text":"We can cross this one out too."},{"Start":"00:51.980 ","End":"00:53.600","Text":"Let\u0027s go on to our next answer."},{"Start":"00:53.600 ","End":"00:56.725","Text":"Carbohydrates, correct; lipids, correct;"},{"Start":"00:56.725 ","End":"00:59.505","Text":"proteins correct, and nucleic acids,"},{"Start":"00:59.505 ","End":"01:00.870","Text":"yes; this is correct."},{"Start":"01:00.870 ","End":"01:02.850","Text":"D, none of the above, that\u0027s wrong."},{"Start":"01:02.850 ","End":"01:06.360","Text":"So our correct answer is carbohydrates,"},{"Start":"01:06.360 ","End":"01:09.590","Text":"which are sugars; lipids,"},{"Start":"01:09.590 ","End":"01:11.300","Text":"which are fats and oils;"},{"Start":"01:11.300 ","End":"01:16.359","Text":"proteins, which are the building blocks and the machinery of our body;"},{"Start":"01:16.359 ","End":"01:20.690","Text":"and nucleic acids, which include RNA and DNA,"},{"Start":"01:20.690 ","End":"01:23.460","Text":"and our correct answer is C."}],"ID":24116},{"Watched":false,"Name":"Exercise 19","Duration":"17s","ChapterTopicVideoID":23278,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.470","Text":"Biological macromolecules are considered organic because,"},{"Start":"00:04.470 ","End":"00:07.470","Text":"well, by definition,"},{"Start":"00:07.470 ","End":"00:10.860","Text":"organic chemistry is the study of carbon compounds."},{"Start":"00:10.860 ","End":"00:13.007","Text":"Therefore, we can say that"},{"Start":"00:13.007 ","End":"00:17.350","Text":"biological macromolecules are organic because they contain carbon."}],"ID":24117},{"Watched":false,"Name":"Exercise 20","Duration":"1m 10s","ChapterTopicVideoID":23279,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.890 ","End":"00:06.345","Text":"Describe the differences and similarities between starch and glycogen."},{"Start":"00:06.345 ","End":"00:09.120","Text":"Let\u0027s start by having a look at starches."},{"Start":"00:09.120 ","End":"00:11.190","Text":"What are starches?"},{"Start":"00:11.190 ","End":"00:14.835","Text":"This is the efficient way that plants store glucose,"},{"Start":"00:14.835 ","End":"00:17.745","Text":"which is a single unit of sugar."},{"Start":"00:17.745 ","End":"00:20.565","Text":"The monosaccharide, the glucose,"},{"Start":"00:20.565 ","End":"00:24.645","Text":"is stored as a long-chain polysaccharide of sugars."},{"Start":"00:24.645 ","End":"00:26.460","Text":"This can be unbranched."},{"Start":"00:26.460 ","End":"00:27.780","Text":"It can miss amylose,"},{"Start":"00:27.780 ","End":"00:31.295","Text":"starch or branch like an amylopectin."},{"Start":"00:31.295 ","End":"00:35.150","Text":"The animal equivalent of starch is the glycogen."},{"Start":"00:35.150 ","End":"00:38.750","Text":"The glycogen is very branched and it\u0027s stored in the liver and"},{"Start":"00:38.750 ","End":"00:42.320","Text":"the muscles while starches are stored in any parts of the plant,"},{"Start":"00:42.320 ","End":"00:43.520","Text":"the seeds, the leaves,"},{"Start":"00:43.520 ","End":"00:45.920","Text":"tubers under the grant, like potatoes."},{"Start":"00:45.920 ","End":"00:49.280","Text":"Therefore, you could sum this all up and say that,"},{"Start":"00:49.280 ","End":"00:52.370","Text":"glycogen and starch are both polysaccharides."},{"Start":"00:52.370 ","End":"00:54.890","Text":"They are the storage form of glucose."},{"Start":"00:54.890 ","End":"00:57.020","Text":"Starch is used by plants."},{"Start":"00:57.020 ","End":"00:59.150","Text":"It can be branched or unbranched and it\u0027s"},{"Start":"00:59.150 ","End":"01:02.270","Text":"stored in cells of the roots, leaves, and seeds."},{"Start":"01:02.270 ","End":"01:05.240","Text":"Glycogen is the animal equivalent of starch."},{"Start":"01:05.240 ","End":"01:09.450","Text":"It\u0027s highly branched and it\u0027s stored in liver and muscle cells."}],"ID":24118},{"Watched":false,"Name":"Exercise 21","Duration":"44s","ChapterTopicVideoID":23280,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.840 ","End":"00:05.740","Text":"Explain the role of lipids in plants or animals?"},{"Start":"00:05.740 ","End":"00:12.550","Text":"First, fat serves as a valuable way for plants and animals to store their energy."},{"Start":"00:12.550 ","End":"00:16.160","Text":"Fat provides insulation from cold."},{"Start":"00:16.160 ","End":"00:19.945","Text":"Waxes are a type of lipid that can protect plant leaves,"},{"Start":"00:19.945 ","End":"00:23.900","Text":"bird feathers, and mammalian fur from getting wet."},{"Start":"00:24.570 ","End":"00:27.640","Text":"Phospholipids and steroids are"},{"Start":"00:27.640 ","End":"00:30.940","Text":"lipids that are an important component of animal cell membranes,"},{"Start":"00:30.940 ","End":"00:35.300","Text":"as well as plant, fungal, and bacterial membranes."},{"Start":"00:35.730 ","End":"00:37.990","Text":"Last but not least,"},{"Start":"00:37.990 ","End":"00:44.180","Text":"lipid hormones like testosterone or estrogen serves as important chemical messengers."}],"ID":24119},{"Watched":false,"Name":"Exercise 22","Duration":"55s","ChapterTopicVideoID":23281,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.170 ","End":"00:07.560","Text":"Explain the consequences of an amino acid substituted for another in a polypeptide chain."},{"Start":"00:07.560 ","End":"00:11.775","Text":"Well, the sequence of amino acids is given to us by the genetic code,"},{"Start":"00:11.775 ","End":"00:16.485","Text":"by the messenger RNA sequence."},{"Start":"00:16.485 ","End":"00:20.220","Text":"If we had a mutation and the genetic code changed,"},{"Start":"00:20.220 ","End":"00:23.820","Text":"we might get a different amino acid in the growing peptide chain."},{"Start":"00:23.820 ","End":"00:27.175","Text":"What would happen is afterwards in the secondary structure."},{"Start":"00:27.175 ","End":"00:32.547","Text":"Secondary structure including the Alpha helix 12 here over the Beta sheets,"},{"Start":"00:32.547 ","End":"00:37.170","Text":"these structures are formed by hydrogen bonds between the different amino acids,"},{"Start":"00:37.170 ","End":"00:38.690","Text":"and if we substitute them,"},{"Start":"00:38.690 ","End":"00:40.700","Text":"we might get a whole different structure."},{"Start":"00:40.700 ","End":"00:43.610","Text":"Could answer here that,"},{"Start":"00:43.610 ","End":"00:46.040","Text":"a change in gene sequence can lead to"},{"Start":"00:46.040 ","End":"00:50.855","Text":"a different amino acid being added to a polypeptide chain instead of the normal one."},{"Start":"00:50.855 ","End":"00:54.990","Text":"This causes a change in protein structure and function."}],"ID":24120},{"Watched":false,"Name":"Exercise 23","Duration":"1m 6s","ChapterTopicVideoID":23282,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:01.310 ","End":"00:06.450","Text":"Describe the differences in the 4 protein structures."},{"Start":"00:06.450 ","End":"00:09.900","Text":"The primary structure of a protein is"},{"Start":"00:09.900 ","End":"00:13.095","Text":"the linear sequence of the amino acids in a protein."},{"Start":"00:13.095 ","End":"00:16.890","Text":"The secondary structure is the regular structure of"},{"Start":"00:16.890 ","End":"00:20.355","Text":"proteins formed by intramolecular hydrogen bonding"},{"Start":"00:20.355 ","End":"00:24.120","Text":"between the oxygen atom of 1 amino acid residue and"},{"Start":"00:24.120 ","End":"00:28.470","Text":"the hydrogen attached to the nitrogen atom of another amino acid residue."},{"Start":"00:28.470 ","End":"00:33.460","Text":"This forms Alpha helix structures, or Beta-pleated sheets."},{"Start":"00:34.340 ","End":"00:39.960","Text":"The tertiary structure is the 3 dimensional conformation of a protein."},{"Start":"00:39.960 ","End":"00:43.640","Text":"It includes interactions between secondary structural of elements,"},{"Start":"00:43.640 ","End":"00:47.755","Text":"and it\u0027s formed from interactions between amino acids side chains."},{"Start":"00:47.755 ","End":"00:51.350","Text":"The quaternary structure is the association and"},{"Start":"00:51.350 ","End":"00:55.535","Text":"interaction between discrete polypeptide units in a protein."},{"Start":"00:55.535 ","End":"01:00.110","Text":"We have here many polypeptides like the tertiary structure,"},{"Start":"01:00.110 ","End":"01:01.310","Text":"which connect with each other."},{"Start":"01:01.310 ","End":"01:04.770","Text":"Each of them has a sub-unit of 1 larger protein."}],"ID":24121},{"Watched":false,"Name":"Exercise 24","Duration":"2m 14s","ChapterTopicVideoID":23283,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.890 ","End":"00:06.060","Text":"What are the structural differences between RNA and DNA?"},{"Start":"00:06.060 ","End":"00:08.895","Text":"Let\u0027s start by looking at the structure of DNA."},{"Start":"00:08.895 ","End":"00:11.355","Text":"The DNA has a double-helix structure."},{"Start":"00:11.355 ","End":"00:13.350","Text":"Double helix means that we have here"},{"Start":"00:13.350 ","End":"00:19.450","Text":"this double twirl because each of the strands is twirled around itself."},{"Start":"00:19.450 ","End":"00:24.440","Text":"The outside of the double helix is the sugar and phosphate."},{"Start":"00:24.440 ","End":"00:26.390","Text":"It is the backbone of the helix."},{"Start":"00:26.390 ","End":"00:29.885","Text":"The nitrogenous bases are in the interior."},{"Start":"00:29.885 ","End":"00:33.740","Text":"Let\u0027s have a look at that. We have here phosphate, sugar, phosphate,"},{"Start":"00:33.740 ","End":"00:35.540","Text":"sugar, and in the opposite strand,"},{"Start":"00:35.540 ","End":"00:37.265","Text":"phosphate, sugar, phosphate, sugar."},{"Start":"00:37.265 ","End":"00:39.650","Text":"Just turn this blue here."},{"Start":"00:39.650 ","End":"00:42.065","Text":"We can see outside of the strand,"},{"Start":"00:42.065 ","End":"00:44.460","Text":"is the outside part."},{"Start":"00:45.530 ","End":"00:51.330","Text":"The interior is the nitrogenous bases here."},{"Start":"00:51.330 ","End":"00:56.950","Text":"This part here. We\u0027ll have them here. That\u0027s how it looks."},{"Start":"00:58.430 ","End":"01:02.130","Text":"The monomers of DNA are the nucleotides."},{"Start":"01:02.130 ","End":"01:04.140","Text":"Here, we have 1 nucleotide,"},{"Start":"01:04.140 ","End":"01:07.085","Text":"and it has a phosphate group here."},{"Start":"01:07.085 ","End":"01:08.900","Text":"This is the phosphate group."},{"Start":"01:08.900 ","End":"01:12.245","Text":"It has 1 of the bases."},{"Start":"01:12.245 ","End":"01:16.715","Text":"Here, we have our base, the nitrogenous bases."},{"Start":"01:16.715 ","End":"01:18.975","Text":"In this example, we have thymine,"},{"Start":"01:18.975 ","End":"01:21.130","Text":"but it can be guanine,"},{"Start":"01:21.130 ","End":"01:24.250","Text":"cytosine, or adenine also."},{"Start":"01:24.250 ","End":"01:27.680","Text":"We have our sugar which is in DNA is deoxyribose,"},{"Start":"01:27.680 ","End":"01:30.800","Text":"which means it\u0027s sugar,"},{"Start":"01:30.800 ","End":"01:33.790","Text":"which is a ribose without the oxygen."},{"Start":"01:34.450 ","End":"01:38.635","Text":"On the other hand, RNA is usually single-stranded,"},{"Start":"01:38.635 ","End":"01:40.395","Text":"maybe a 1 strand of it."},{"Start":"01:40.395 ","End":"01:42.495","Text":"It\u0027s made of ribonucleotides,"},{"Start":"01:42.495 ","End":"01:44.690","Text":"and that means similar to the other nucleotides,"},{"Start":"01:44.690 ","End":"01:46.150","Text":"you just solved DNA,"},{"Start":"01:46.150 ","End":"01:49.220","Text":"but the sugar is ribose and deoxyribose."},{"Start":"01:49.220 ","End":"01:52.145","Text":"They are linked by phosphodiester linkages."},{"Start":"01:52.145 ","End":"01:55.009","Text":"A ribonucleotide contains ribose,"},{"Start":"01:55.009 ","End":"01:56.945","Text":"that\u0027s the pentose sugar that we saw."},{"Start":"01:56.945 ","End":"01:59.375","Text":"1 of the 4 nitrogenous bases,"},{"Start":"01:59.375 ","End":"02:03.010","Text":"A, U, G or C while T,"},{"Start":"02:03.010 ","End":"02:05.240","Text":"thymine of DNA,"},{"Start":"02:05.240 ","End":"02:09.725","Text":"is substituted for uracil and of course, a phosphate group."},{"Start":"02:09.725 ","End":"02:11.480","Text":"We can see it here in yellow."},{"Start":"02:11.480 ","End":"02:14.520","Text":"It\u0027s the backbone of the RNA strand."}],"ID":24122},{"Watched":false,"Name":"Exercise 25","Duration":"37s","ChapterTopicVideoID":23284,"CourseChapterTopicPlaylistID":108177,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.980 ","End":"00:05.745","Text":"What are the 3 types of RNA and how do they function?"},{"Start":"00:05.745 ","End":"00:08.730","Text":"Messenger RNA, or in short,"},{"Start":"00:08.730 ","End":"00:12.480","Text":"mRNA, is the mediator between DNA and proteins."},{"Start":"00:12.480 ","End":"00:15.990","Text":"The mRNA is copied from the DNA sequence,"},{"Start":"00:15.990 ","End":"00:19.995","Text":"and the protein is built on the sequence of the mRNA."},{"Start":"00:19.995 ","End":"00:22.860","Text":"Transfer RNA, or tRNA,"},{"Start":"00:22.860 ","End":"00:27.300","Text":"carries a single amino acid to the site of protein synthesis."},{"Start":"00:27.300 ","End":"00:31.245","Text":"Ribosomal RNA, or in short, rRNA,"},{"Start":"00:31.245 ","End":"00:33.698","Text":"is a major constituent of the ribosome,"},{"Start":"00:33.698 ","End":"00:37.390","Text":"the cellular machine that synthesizes proteins."}],"ID":24123}],"Thumbnail":null,"ID":108177}]

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