Sentence stringlengths 158 2.09k | video_title stringlengths 11 104 |
|---|---|
And a plasmid is a piece of genetic material that sits outside of chromosomes but that can reproduce along, or that could, I guess we could say, can replicate along with the machinery of the, or the genetic machinery of the organism. Or it could even express itself just like the genes of the organism that are in the ch... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And then we want to paste it, then we want to paste it into a plasmid. And plasmids tend to be circular DNA. So we will paste it into a plasmid. And in order for them to fit, there's oftentimes these overhangs over here. So you might have an overhang over there. You might have an overhang over there. And so the plasmid... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And in order for them to fit, there's oftentimes these overhangs over here. So you might have an overhang over there. You might have an overhang over there. And so the plasmid that we're placing in might have complementary base pairs over the overhangs, which will allow it easier, it will become easier for them to reac... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And so the plasmid that we're placing in might have complementary base pairs over the overhangs, which will allow it easier, it will become easier for them to react with each other if they have these overhangs. So let me, we're pasting it into the plasmid. And this is amazing because obviously, DNA, this isn't stuff th... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
You're making these solutions and you're applying the restriction enzymes. The restriction enzymes are just in mass cutting these things. They're bumping in just the right way to cause this reaction to happen. Then you're taking those genes and then you're putting them with the plasmids that happen to have the right se... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
Then you're taking those genes and then you're putting them with the plasmids that happen to have the right sequences at their ends so that they match up. And then you also put in a bunch of DNA ligase, DNA ligase, to connect the backbones right over here. And we also saw DNA ligase when we studied replication. So that... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
So that is DNA ligase, which you can think of it as helping to do, helping to do the pasting. And so now we have this plasmid and we want to insert it into an organism that can make the copies for us. And an organism that's typically used is, or a type of organism is bacteria, and E. coli in particular. And so what we ... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And so what we could do is, we could, let's say that we have a bunch of, let's say you have a vial right over here. You have a vial and it has a solution in it with a bunch of E. coli. A bunch of E. coli. And you actually wouldn't be able to see it visually. But there's E. coli in that solution. And then you would put ... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And you actually wouldn't be able to see it visually. But there's E. coli in that solution. And then you would put your plasmids, which would be even harder to see, in that solution. And somehow we want the E. coli, we want the bacteria to take up the plasmid. And the technique that's typically done is giving some type... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And somehow we want the E. coli, we want the bacteria to take up the plasmid. And the technique that's typically done is giving some type of a shock to the system that makes the bacteria take up the plasmids. And the typical shock is a heat shock. And this isn't fully understood how the heat shock works, but it does. A... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And this isn't fully understood how the heat shock works, but it does. And so people have been using this for some time. So if you have a bacteria, you have a bacteria right over here. It has its existing DNA. So this is its existing genetic material right over there. Let me label this. This is the bacteria. | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
It has its existing DNA. So this is its existing genetic material right over there. Let me label this. This is the bacteria. You put it in the presence of our plasmids. So you put it in the presence of our plasmid and you apply the heat shock. And some of that bacteria is going to take in the plasmid. | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
This is the bacteria. You put it in the presence of our plasmids. So you put it in the presence of our plasmid and you apply the heat shock. And some of that bacteria is going to take in the plasmid. It's going to take in the plasmid. And so just like that, it's going to take it in. And so what you then do is you place... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And some of that bacteria is going to take in the plasmid. It's going to take in the plasmid. And so just like that, it's going to take it in. And so what you then do is you place the solution that has your bacteria, some of which will have taken up the plasmid, and you put it, and then you try to grow the bacteria on ... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And so what you then do is you place the solution that has your bacteria, some of which will have taken up the plasmid, and you put it, and then you try to grow the bacteria on a plate. So let me draw that. So let me draw. So here we have a plate to grow our bacteria on. And it has nutrients right over here that bacter... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
So here we have a plate to grow our bacteria on. And it has nutrients right over here that bacteria can grow on. It has nutrients. It has nutrients. And so you could say, okay, we'll put this here, and then a bunch of bacteria will just grow. So you would see things like this, which would be many, many, many, many cell... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
It has nutrients. And so you could say, okay, we'll put this here, and then a bunch of bacteria will just grow. So you would see things like this, which would be many, many, many, many cells of bacteria. There would be colonies of bacteria. You could just let them grow. But there's a problem here. Because I mentioned s... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
There would be colonies of bacteria. You could just let them grow. But there's a problem here. Because I mentioned some of the bacteria will take up the plasmids and some won't. And so you won't know, hey, when this bacteria, when it keeps replicating, it might form one of these colonies. So this is a colony that you l... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
Because I mentioned some of the bacteria will take up the plasmids and some won't. And so you won't know, hey, when this bacteria, when it keeps replicating, it might form one of these colonies. So this is a colony that you like. So this one is a good colony. Put a check mark there. But maybe this colony is formed by a... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
So this one is a good colony. Put a check mark there. But maybe this colony is formed by a initial bacteria or a set of bacteria that did not take up the plasmid. So it won't contain the actual gene in question. So you don't want that one. So how do you select for the bacteria that actually took up the plasmid? Well, w... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
So it won't contain the actual gene in question. So you don't want that one. So how do you select for the bacteria that actually took up the plasmid? Well, what you do is, besides the gene that you care about, that you want to make copies of, you also place a gene for antibiotic resistance in your plasmid. So now you h... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
Well, what you do is, besides the gene that you care about, that you want to make copies of, you also place a gene for antibiotic resistance in your plasmid. So now you have a gene for antibiotic resistance here. And so only the bacteria, and I think it's amazing that we as humanity are able to do these types of things... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And so what you do is, in your nutrients, you put nutrients plus antibiotics, plus an antibiotic, antibiotic. And so this one will survive because it has that resistance. It has that gene that allows it to not be susceptible to the antibiotics. But these are not going to survive. They're not even going to happen. They'... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
But these are not going to survive. They're not even going to happen. They're not even going to grow because there's antibiotics mixed in with those nutrients. And so this is a pretty cool thing. You start with the gene that you cared about. You cut and pasted it into our plasmid. Let me write the labels down. | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And so this is a pretty cool thing. You start with the gene that you cared about. You cut and pasted it into our plasmid. Let me write the labels down. Into our plasmid that also contained a gene that gave antibiotic resistance to any bacteria that takes up the plasmid. You put these plasmids in the presence of the bac... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
Let me write the labels down. Into our plasmid that also contained a gene that gave antibiotic resistance to any bacteria that takes up the plasmid. You put these plasmids in the presence of the bacteria. You provide some type of a shock, maybe a heat shock, so that some of the bacteria takes it up. And then the bacter... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
You provide some type of a shock, maybe a heat shock, so that some of the bacteria takes it up. And then the bacteria starts reproducing. And as it reproduces, it also is reproducing the plasmids. And because it has this antibiotic resistance, it is going to grow on this nutrient-antibiotic mixture, and the other bacte... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
And because it has this antibiotic resistance, it is going to grow on this nutrient-antibiotic mixture, and the other bacteria that did not take up the plasmids are not going to grow. And so just like that, you can take this, you can take this colony right over here and put it into another solution or continue to grow ... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
How do you make use of it? Well, the bacteria themselves, let's say that gene is for something you want to manufacture, say insulin for diabetics. Well, you could actually use that bacteria's machiner. We use its reproductive machinery to keep replicating the genetic information, but you can also use its productive mac... | DNA cloning and recombinant DNA Biomolecules MCAT Khan Academy.mp3 |
Because without this ability, the animal is not likely to be able to survive and reproduce. But this behavior is an interesting one because there's kind of a cost-benefit analysis that's associated with it. Obviously, an animal needs to be able to do it to survive, but going out and getting food can actually take up a ... | Animal behavior foraging Individuals and Society MCAT Khan Academy.mp3 |
So the animal needs to use energy in order to gain it. And so the goal with foraging is always to figure out how to get the highest energy yield while expending the least amount of energy doing it. And the term foraging actually refers to a bunch of different behaviors. For example, it can include looking for food, lik... | Animal behavior foraging Individuals and Society MCAT Khan Academy.mp3 |
For example, it can include looking for food, like this antelope right here who's eating grass. But it can also include things like stalking prey, which we can see in this picture with a tiger chasing antelope. There are two main foraging strategies that an animal can use. And it's actually what we see the tiger doing ... | Animal behavior foraging Individuals and Society MCAT Khan Academy.mp3 |
And it's actually what we see the tiger doing in this picture right here, and that's solitary foraging. And actually, let me write that in orange to represent the tiger. So solitary foraging is exactly what it sounds like. It's when an animal looks for food by itself. The second type of foraging we see is group foragin... | Animal behavior foraging Individuals and Society MCAT Khan Academy.mp3 |
It's when an animal looks for food by itself. The second type of foraging we see is group foraging, and that's what lions do, and so I'll write that in yellow here. And this is when animals look for food in groups. And one thing that's both good and bad about this strategy is that in this case, hunting would not only d... | Animal behavior foraging Individuals and Society MCAT Khan Academy.mp3 |
And one thing that's both good and bad about this strategy is that in this case, hunting would not only depend on your own behavior, but also the behavior of those around you. And so this can actually lead to competition within a group, especially when resources are scarce. But there can also be many benefits to this s... | Animal behavior foraging Individuals and Society MCAT Khan Academy.mp3 |
Let's say that we're starting with a population of 1,000 rabbits, and we know that this population is growing at 10% per month. What I want to do is explore how that population will grow if it's growing 10% per month. So let's set up a little bit of a, let's set up a little table here, a little table. And on this left ... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
And on this left column, let's just say this is the number of months that have gone by, and on the right column, let's say this is the population. So we know from the information given to us that at zero months, we're starting off with 1,000 rabbits. Now let's think about what's going to happen after one month. Well, o... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
Well, our population's going to grow by 10%, so we could take our population at the beginning of the month, and growing by 10%, that's the same thing as multiplying by 1.1. You have your original population, and then you grow it by 10%. One plus 10% is 1.1, so we can multiply it by 1.1. And that math we can do in our h... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
And that math we can do in our head, it is 1,100, or 1,100. But let's just write this as 1,000 times 1.1, not 1.5, times 1.1. Now let's think about what happens as we go to month two. Well, it's going to be the population that we started at the beginning of the month times 1.1 again. So it's going to be the population ... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
Well, it's going to be the population that we started at the beginning of the month times 1.1 again. So it's going to be the population at the beginning of the month, which was that, which we have right over there. But then we're going to multiply by 1.1 again. Or we can just say that this is 1.1 squared. And I think y... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
Or we can just say that this is 1.1 squared. And I think you see a pattern emerging. After another month, the population's going to be 1,000 times 1.1 to the third power. We're just going to multiply by 1.1 again. And so if you were to go n months into the future, well, you could see what's going to be. It's going to b... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
We're just going to multiply by 1.1 again. And so if you were to go n months into the future, well, you could see what's going to be. It's going to be 1,000 times, or being multiplied by 1.1 n times, or 1,000 times 1.1 to the nth power. And so we can set up an expression here. We could say, look, the population, let's ... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
And so we can set up an expression here. We could say, look, the population, let's say that the population is p. The population as a function of n, as a function of n, is going to be equal to our initial population, our initial population, times 1.1 to the nth power. And you might say, okay, well, this makes sense. It ... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
It doesn't look like we're getting crazy numbers. But just for kicks, let's just think about what's going to happen in 10 years. So 10 years would be 120 months. So the population at the end of 120 months is going to be 1,000 times 1.1 to the 120th power. And so let's, let me get a calculator out to do that. I cannot c... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
So the population at the end of 120 months is going to be 1,000 times 1.1 to the 120th power. And so let's, let me get a calculator out to do that. I cannot calculate 1.1 to the 120th power in my head. 1.1 to the 120th power is equal to that times our initial population. So times 1,000, one, two, three, is going to be ... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
1.1 to the 120th power is equal to that times our initial population. So times 1,000, one, two, three, is going to be equal to roughly 93 million rabbits. Let me write that down. So we started with 1,000, and we're going to have approximately 93 million rabbits. 93 million, million rabbits. And so we grew by a factor o... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
So we started with 1,000, and we're going to have approximately 93 million rabbits. 93 million, million rabbits. And so we grew by a factor of 93,000 over 10 years. So over another 10 years, we'd grow by 93,000 times this. And so you quickly realize 10% per month is quite fast. And this might seem extremely fast, but t... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
So over another 10 years, we'd grow by 93,000 times this. And so you quickly realize 10% per month is quite fast. And this might seem extremely fast, but this is actually not outlandish for a population of rabbits that are not limited by space, or predators, or food. And if you were to plot something like this out, if ... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
And if you were to plot something like this out, if you were to plot the rabbit population with respect to time, you would see a graph that looks, let me draw it. So this axis, it is time, say in months. And this axis, you have your population. You have your population. This type of function, or this type of equation, ... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
You have your population. This type of function, or this type of equation, let me see, population, I, population, this is an exponential function. And so your population as a function of time is going to look like this. It's going to have this kind of hockey stick J shape right over here. And if you let these rabbits r... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
It's going to have this kind of hockey stick J shape right over here. And if you let these rabbits reproduce long enough, they would frankly take over the planet if they had enough food and if they had enough space to do it. But as you notice, I keep saying, if they have enough food and if they have enough space. The r... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
The reality in the world is that there is not infinite food and infinite space, and it isn't the case that there are no predators or competition for resources. And so there is actually a maximum carrying capacity for a certain part of the environment for a certain type of species. And so what's more likely to happen, w... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
Exponential growth. And why is it called exponential growth? Well, you notice, we are growing by the input, which is time, is being thrown into our exponent. And so that is exponential growth. But obviously you can't have an infinite number of rabbits or you just can't grow forever. There is going to be some natural ma... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
And so that is exponential growth. But obviously you can't have an infinite number of rabbits or you just can't grow forever. There is going to be some natural maximum carrying capacity that the environment can actually sustain. And so the actual growth that you would see, when the population is well below that carryin... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
And so the actual growth that you would see, when the population is well below that carrying capacity, it's reasonable to model it with exponential growth. But as it gets closer and closer to that carrying capacity, it is going to asymptote up towards it. So it's gonna get up towards it, but not cross it. And that's ju... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
And that's just a model. There are other situations where maybe it goes up to it and it crosses it and then it cycles around it. So these are all different ways of thinking about it. But the general idea is you wouldn't expect something to just grow unfettered forever. Now this blue curve, which people often use to mod... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
But the general idea is you wouldn't expect something to just grow unfettered forever. Now this blue curve, which people often use to model populations, especially when they're thinking about the populations once they approach the environment's carrying capacity, this is this kind of S-shaped curve. That is considered,... | Exponential and logistic growth in populations Ecology Khan Academy.mp3 |
The whole process of natural selection is to some degree dependent on the idea of variation, that within any population of a species, you have some genetic variation. So for example, let's say I have a bunch of, well, this is the circle species. And one guy is that color, and then I've got a bunch more. Maybe some are ... | Variation in a Species (3).mp3 |
Maybe some are that color. That's the same color. That one, and that one, and that one. And for whatever reason, sometimes there are no environmental factors that will predispose one of these guys to be able to survive and reproduce over the other. But every now and then, there might be some environmental factor. And i... | Variation in a Species (3).mp3 |
And for whatever reason, sometimes there are no environmental factors that will predispose one of these guys to be able to survive and reproduce over the other. But every now and then, there might be some environmental factor. And it makes maybe all of a sudden, this guy is more fit to reproduce. And so for whatever re... | Variation in a Species (3).mp3 |
And so for whatever reason, this guy is able to reproduce more frequently, and these guys less frequently. And some of them get killed or whatever, eaten by birds or they're just not able to reproduce for whatever reason. And then maybe these guys are something in between. And so over time, the frequency of the differe... | Variation in a Species (3).mp3 |
And so over time, the frequency of the different traits you see in this population will change. And if they are drastic enough, maybe these guys start becoming dominant and start not liking these guys because they're so different or whatever else. We could see a lot of different reasons. This could eventually turn into... | Variation in a Species (3).mp3 |
This could eventually turn into a different species. Now, the obvious question is, what leads to this variation? In a population, what leads to this? In fact, even in our population, what leads to one person having dirty blonde hair, one person having brown hair, one person having black hair, and the spectrum of skin c... | Variation in a Species (3).mp3 |
In fact, even in our population, what leads to one person having dirty blonde hair, one person having brown hair, one person having black hair, and the spectrum of skin complexions and heights is pretty much infinite? What causes that? And then one thing that I kind of point to, and we talked about this a little bit in... | Variation in a Species (3).mp3 |
The DNA, we learned, is just a sequence of these bases. So adenine, guanine, let's say I got some thymine going, I have some more adenine, some cytosine. And that these code, if you have enough of these in a row, maybe you have a few hundred or a few thousands of these, these code for proteins or they code for things t... | Variation in a Species (3).mp3 |
But maybe you have a change in one of them. Maybe this cytosine, for whatever reason, becomes a guanine randomly. Or maybe these get deleted. And that would change the DNA. But you can imagine, if I went to someone's computer code and just randomly started changing letters and randomly started inserting letters without... | Variation in a Species (3).mp3 |
And that would change the DNA. But you can imagine, if I went to someone's computer code and just randomly started changing letters and randomly started inserting letters without really knowing what I'm doing, most of the time I'm going to break the computer program. Most of the time, the great majority of the time, th... | Variation in a Species (3).mp3 |
For example, if I go into someone's computer program and if I just add a couple of spaces or something, that might not change their computer program. But if I start getting rid of semicolons and start changing numbers and all that, it'll probably make the computer program break. So it'll either do nothing or it'll actu... | Variation in a Species (3).mp3 |
Mutations. Sometimes they might make the actual cell kind of go run amok and we'll do a whole maybe series of videos on cancer and that itself obviously would hurt the organism as a whole. Although if it occurs after the organism is reproduced, it might not be something that selects against the organism. But anyway, an... | Variation in a Species (3).mp3 |
But anyway, and it also wouldn't be passed on. But anyway, I won't go too detailed into that. But the whole point is that mutations don't seem to be a satisfying source of variation. They could be a source or kind of contribute on the margin, but there must be something more profound than mutations that's creating the ... | Variation in a Species (3).mp3 |
They could be a source or kind of contribute on the margin, but there must be something more profound than mutations that's creating the diversity even within, or maybe I should call the variation, even within a population. And the answer here is really, it's kind of right in front of us. It really addresses kind of on... | Variation in a Species (3).mp3 |
And it's so fundamental that a lot of people never even question why it is the way it is. And that is sexual reproduction. And when I mean sexual reproduction, it's this notion that you have, and pretty much if you look at all organisms that have nucleuses, and we call those eukaryotes, maybe I'll do a whole video on e... | Variation in a Species (3).mp3 |
But it's the notion that if you look universally all the way from plants, not universally, but if you look at cells that have nucleuses, they almost universally have this phenomenon that you have males and you have females. In some organisms, an organism can be both a male and a female, but the common idea here is that... | Variation in a Species (3).mp3 |
Maybe other cells would just butt off from me, and then randomly one cell might be a little bit different and whatever else. But that would, as we already talked about, most of the time we would have very little change, very little variation. And whatever variation does occur because of any kind of noise being introduc... | Variation in a Species (3).mp3 |
Most of the times it'll break the organism. Now, when you have sexual reproduction, what happens? Well, you keep mixing and matching every possible combination of DNA in a species pool of DNA. Let me make this a little bit more concrete for you. So let me erase this horrible drawing I just did. So we all have, let me s... | Variation in a Species (3).mp3 |
Let me make this a little bit more concrete for you. So let me erase this horrible drawing I just did. So we all have, let me stick to humans because that's what we are. We have 23 pairs of chromosomes, and in each pair we have one chromosome from our mother and one chromosome from our father. So let me draw that. So I... | Variation in a Species (3).mp3 |
We have 23 pairs of chromosomes, and in each pair we have one chromosome from our mother and one chromosome from our father. So let me draw that. So I'll do my father's chromosomes in blue, so I have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and I'm running out of space. Let me do more here. 16, 17, 18, 19, 20... | Variation in a Species (3).mp3 |
Let me do more here. 16, 17, 18, 19, 20, 21, 22. And then I'll throw another one here that looks a little bit different. I'll throw one here that looks like a Y. And we'll talk more about the X's and the Y chromosomes. And I have 23 chromosomes from my mother. And not to be stereotypical, but maybe I'll do that in a mo... | Variation in a Species (3).mp3 |
I'll throw one here that looks like a Y. And we'll talk more about the X's and the Y chromosomes. And I have 23 chromosomes from my mother. And not to be stereotypical, but maybe I'll do that in a more feminine color. Let's see. So I have 23 chromosomes from my mother. 1, 2, I just have to draw 1, 3, 4, 5, 6, 7, 8, 9, ... | Variation in a Species (3).mp3 |
And not to be stereotypical, but maybe I'll do that in a more feminine color. Let's see. So I have 23 chromosomes from my mother. 1, 2, I just have to draw 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. So what's going on here? I have 23 from my mother. I have 23 from my father. | Variation in a Species (3).mp3 |
1, 2, I just have to draw 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. So what's going on here? I have 23 from my mother. I have 23 from my father. Now, each of these chromosomes, and I made them right next to each other. So for example, let me zoom in on one pair of these. So let's s... | Variation in a Species (3).mp3 |
I have 23 from my father. Now, each of these chromosomes, and I made them right next to each other. So for example, let me zoom in on one pair of these. So let's say we look at chromosome number 3. So let me zoom in on chromosome number 3. I have one from my mother right here. And remember, actually maybe I'll do it th... | Variation in a Species (3).mp3 |
So let's say we look at chromosome number 3. So let me zoom in on chromosome number 3. I have one from my mother right here. And remember, actually maybe I'll do it this way. Remember, a chromosome is just a big, if you take the DNA, it just keeps wrapping around. It actually wraps around all these proteins and it crea... | Variation in a Species (3).mp3 |
And remember, actually maybe I'll do it this way. Remember, a chromosome is just a big, if you take the DNA, it just keeps wrapping around. It actually wraps around all these proteins and it creates the structure. But it's just a big, you see it like that, you're like, oh, maybe the DNA, no, but this could have million... | Variation in a Species (3).mp3 |
But it's just a big, you see it like that, you're like, oh, maybe the DNA, no, but this could have millions of base pairs. So maybe it'll look something like that. It's a densely wrapped version of, well, it's a long string of DNA, and when it's normally drawn like this, which is not always the way it is, and we'll tal... | Variation in a Species (3).mp3 |
So let's say that's from my mother and that's from my father. Now, these are both, we call them, I'll call them, they're the same, let's call this chromosome 3. They're both chromosome 3. And what the idea is here is that I'm getting different traits from my father and from my mother. For example, and I'm doing a gross... | Variation in a Species (3).mp3 |
And what the idea is here is that I'm getting different traits from my father and from my mother. For example, and I'm doing a gross oversimplification here, but this is really to just give you the idea of what's going on. This chromosome 3, maybe it contains this trait for hair color. And maybe my father had, and I'll... | Variation in a Species (3).mp3 |
And maybe my father had, and I'll use my actual example, my father had very straight hair. So let's say he had, some place on this chromosome, there is a gene for hair straightness. Let's say it's a little thing right there. And remember, that gene could be thousands of base pairs. But let's say this is hair straightne... | Variation in a Species (3).mp3 |
And remember, that gene could be thousands of base pairs. But let's say this is hair straightness. So my father's version of that gene, or he had the allele for straightness. And remember, an allele is just a version of a gene. So I'll call it the allele straight for straight hair. Now, this other chromosome that my mo... | Variation in a Species (3).mp3 |
And remember, an allele is just a version of a gene. So I'll call it the allele straight for straight hair. Now, this other chromosome that my mother gave me, this essentially, and there are exceptions, but for the most part, it codes for the same genes. And that's why I put them next to each other. So this will also h... | Variation in a Species (3).mp3 |
And that's why I put them next to each other. So this will also have the gene for hair straightness or curliness. But my mom does happen to actually have curly hair. So she has the gene right there for curly hair. So she has the version of the gene here is, let's see, allele curly. The gene just says, look, this is the... | Variation in a Species (3).mp3 |
So she has the gene right there for curly hair. So she has the version of the gene here is, let's see, allele curly. The gene just says, look, this is the gene for whether or not your hair is curly. Each version of the gene is called an allele. Allele curly. Now, when I got both of these in my body, or in my cells, and... | Variation in a Species (3).mp3 |
Each version of the gene is called an allele. Allele curly. Now, when I got both of these in my body, or in my cells, and this is in every cell of my body, every cell of my body except for, and we'll talk a little in a few seconds about my germ cells, but every cell other than the ones that I use for reproduction have ... | Variation in a Species (3).mp3 |
But only certain chromosomes are, for example, these genes will be completely useless in my fingernails because all of a sudden, the straight and the curly don't matter that much. And I'm simplifying. Maybe they will on some other dimension. But let's say for simplicity, they won't matter in certain places. So certain ... | Variation in a Species (3).mp3 |
But let's say for simplicity, they won't matter in certain places. So certain genes are expressed in certain parts of the body, but every one of your body cells, and we call those somatic cells, and we'll separate those from the sex cells or the germ cells that we'll talk about later. So this is my body cells. So this ... | Variation in a Species (3).mp3 |
So this is the great majority of your cells. And this is opposed to your germ cells. And the germ cells, I'll just write it here just so you get it clear, for a male, that's the sperm cells. And for a female, that's the egg cells or the ova. But most of my cells have a complete collection of these. What I want to give ... | Variation in a Species (3).mp3 |
And for a female, that's the egg cells or the ova. But most of my cells have a complete collection of these. What I want to give you the idea is that for every trait, I essentially have two versions, one from my mother and one from my father. Now these right here are called homologous chromosomes. Chromosomes, homologo... | Variation in a Species (3).mp3 |
Now these right here are called homologous chromosomes. Chromosomes, homologous. What that means is every time you see the prefix homologous, or if you see like homo sapien, or even the word homosexual or homogeneous, it means same. You see that all the time. So homologous means that they're almost the same. They're co... | Variation in a Species (3).mp3 |
You see that all the time. So homologous means that they're almost the same. They're coding for the most part the same set of genes, but they're not identical. They actually might code for slightly different versions of the same gene. So depending on what versions I get, what is actually expressed for me. So my genotyp... | Variation in a Species (3).mp3 |
They actually might code for slightly different versions of the same gene. So depending on what versions I get, what is actually expressed for me. So my genotype, let me introduce another word. And I'm overwhelming you with words here. So my genotype is exactly what alleles I have, what versions of the gene. So I got l... | Variation in a Species (3).mp3 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.