 Now, Mendel, from the results of that, you know, F2 cross, where all of a sudden the characteristic, the phenotype that had disappeared in the F1 generation reappeared, he figured out that somehow, during gamete formation, there was a segregation. The alleles, the possible alleles were segregating. We know that that happens in anaphase, right? This is when homologous chromosomes separate, and sister chromatids separate during anaphase, and each one of those alleles goes separately into the gametes. We can do, we can be methodical about our crosses and see this in action. So I'm going to go ahead and model. We're going to do basically the flower color cross that Mendel did, and you remember that he started out with true breeding purple plant, purple flowered plant, you know what I mean, yes, and he crossed it with a true breeding white flowered plant, and then he went through this whole counting of the babies, and he called this his P generation, right? Like these are the parents, and the parents are going to make an F1 generation of babies. I'm going to show you how we can figure out, given this information, how we can figure out what that F1 generation actually looks like. So the, we're going to go through this in a methodical way, and there are four steps to solving heredity problems, and you do them every single time. The first step is done for you. In this case, you have to determine parent phenotypes. Sometimes this is given to you. Other times you have to figure it out based on the other information in the cross, or in the problem that you're given. In our case, the parent phenotypes are the problem, like we know that we have purple flowered parents and white flowered parents, and they are going to make babies. So the phenotypes of the parents, cha-ching done. The next step is to determine the parent genotype. Now, this one's not given to us. It's not directly given to us. What are our possibilities for genotypes? Well, we do know that white flowers are recessive. I don't remember what letter I used for flowers. Do you? Was it P? Um, flower color, P. Okay, that's good. We'll just try to keep it a little bit consistent. So white flowers were recessive. The phenotype of the parent has to be little P, little P. Do you agree with that? We don't have any other option if we're going to have a white parent. But we do have options for our genotype with a purple parent, because we can be homozygous dominant or heterozygous. How do we know? I'm going to tell you right now that you know which one it is. If it's heterozygous or homozygous dominant, you know, and how. How do you know? I can't hear you. Yell louder. Just kidding. Don't yell wherever you are. Or do you do you yell or don't yell? I will tell you the answer. The parents were true breeding. That was the clue. Did I say that in this section? Or did you have to remember that from the last one? I don't know. But that's how you know what the parent genotype is. If it's true breeding, it must be homozygous. And you will be able to convince yourself of that soon. So we can say, OK, we're going to do a homozygous dominant critter by a homozygous recessive critter. OK, step three. Step three always is to determine the possible gametes produced by each parent. Now in the world of rigs, we now imagine meiosis taking place. And because I love you and I can't help it, I just want to remind you that these are alleles on chromosomes. Like, we don't draw in the chromosomes every time, but that's all it is. Is a little chunk of DNA on a chromosome. And in the purple parent, it's in the same location as it is in the white parent. It's just a different allele, a different form of the gene. Our purple parent, what are the possible gametes? Imagine that guy going through meiosis and anaphase twice. And what are all the possible gametes going to be in this case? They have big P alleles, and that's it. OK, they have a whole bunch of other alleles, but we're only keeping track of one at a time. And the one at a time is, I don't know what that is, it's big P. Every possible gamete is big P. And you can show your gametes however you want. I personally like throwing my gametes in to, I shouldn't throw them into both into sperm, but whatever. Sperm tails are fun. All my white parent gametes all are little P. We don't have any other gamete to donate. This is critical. Step four is to build a punnett. OK, no. That's the tool we're going to use to do the task, which is determine, I'm going to write all that down. What are all your possible offspring? You know those problems? I think there are probability problems where they say, what are all the possible ways you can combine four letters of the alphabet if, like, whatever, we did it. We've been doing those kinds of things. We've been doing math to do those kinds of probability things. This determining the possible offspring, a punnett square, is a methodical tool that we can use to quantify possible offspring. You might be like, dude, hello, we don't have to use a square. And I know you don't, but you will. So it's easier to just do it, like show your work in math. Just make the square, even though you're like, I don't need to. I know what the answer is. What are all the possible offspring? Well, gametes from purple parent are big P. Gametes from white parent are little P. 100% of our gametes have to get a big P from one parent and a little P from the other parent. They're all going to be heterozygous. But here's how we set up a punnett square. We put gametes from one parent on one wall, gametes from the other parent on the other wall, and then combine them in the middle. 100% of our kids are heterozygous. And what's their phenotype? Their genotype is heterozygous. What is their phenotype? Heterozygous purple plants. Yes, because they have one copy of the dominant allele. OK, you made a punnett square. Homeboy punnett, his name was Reginald, Reginald-Krundel. Reginald-Krundel punnett came up with this punnett square strategy. And Reginald-Krundel really does make it easier for us to make sure we are able to visualize all the possibilities. Is it that easy? No, let's go find out. Let's do. We did P to F1. Let's take our F1 generation, all those heterozygous purple P plants, and let's do a monohybrid cross. A monohybrid cross is when we take two heterozygotes for one trait, mono one, heterozygotes hybrid. Our monohybrid cross is going to be a little more complicated than this, but same tool. Let's do it.