The law of segregation

18:31let's say let's say the the the the trait that we're looking for is the color of the flower. And we're going to denote the type of alil by a capital A if it's dominant and a lowercase A if it's recessive. Okay. Now, if I have something that's true breeding, that means that I have two copies of the same dominant alil. Capital A, capital A, that's the one on the left up. And then the white true breeding is going to be lowercase A, lowerase A for recessive recessive. Okay? Now, when I cross them, there's going to be four different ways to choose the A and the A, right? I can choose the first capital A and either of

19:11the two lower cases or the second capital A and all. That's four total. But every single time I'm going to get a capital A and a lowercase A. So that first generation is going to have at least one dominant >> copy capital A all the time. Every single one is going to have a capital A and a lower case A. And because the capital A is present, >> the dominant is present. I'm going to get the dominant phenotype >> and the thing is going to be purple. But now let's take the first generation that capital A lowercase A, which we're going to call hetererozygous because there's heterero there's two different copies, >> right? One of each, one, >> one of each. Yeah. Compared to homozygous, which is what we had in the parent generation, that true breeding is now what we call homozygous. So if we

19:53take two hetererozygous parents >> and we cross them now, combinotaurically, >> I'm going to get three offspring that have at least a capital A. There's actually going to be one that's kind of like the true breeding parent. >> Yes. >> In the beginning, the capital A, capital A right? >> That's the one we have in this top left. >> Yeah. in in the in the square. Those are called punit squares. Now, but um the top left, that's capital A, capital A. That's going to be purple. The two on the off diagonal, that's going to have a capital A and a lowerase A. But because there's at least one, I'm still going to get purple. And only one out of the four is going to have homozygous recessive lowerase A,

20:34lowerase A, and that's what's going to be white. >> This is this is interesting. And and I think a key point here is we had the pure the the pure breed generation at first. Two dominants from one the purple, two recessives from the white. The first generation because you always are going to have that dominant from the purple from the one side. You're always ever going to get this dominant recessive combo. >> Yeah. >> And so the reason why that first gen first gen >> always has dominant. And so that's why there you you don't ever see the white, >> right? because it's always being basically overrun by the recessive white is being overrun by the the the dominant. >> The thing that the where you get the diversity of color

21:14begins to arise