 All right, dihybrid cross coming at you. Are you ready? I'm going to tell you the phenotype of the parents. And here's what I'm going to tell you. We're going to have a heterozygous tall purple plant with a heterozygous tall purple plant. Okay, that's your problem. That's all I'm going to tell you. I'm not going to tell you anything else. What you're going to tell me now, what's the genotype of these parents? Tall, do you remember the trait, the tall trait? Tall is actually a dominant trait. But this guy's heterozygous. I probably should tell you that this guy's heterozygous for both traits. So here's how I like to keep my traits together. Again, your bookkeeping doesn't matter, but I'm going to say my heterozygous tall purple parent is going to have this genotype. Both traits are, what's the word? Heterozygous, so I've got a capital and a lower case, a dominant and a recessive allele. Because again, remember, now we're dealing with two different chromosomes. Now's where we get to see the outcome of independent assortment. We also, our other parent, has exactly the same genotype. There you go. After we figure out the genotype, we have to figure out the possible gametes. And the possible gametes. This is where you have to visualize meiosis. Once again, in this time, it might be a little more difficult. This is where you can visualize the independent assortment section of the lecture on meiosis, where you can see that we can line up our dominant alleles together on the same side or not. So watch all my possible gametes. I have to have at least one copy of each gene in my gamete for my gamete to be functional. So I have to have a T allele and a P allele. And I always go, okay, we could have two capitals together. Which means we could also have two recessives together. If we lined up our alleles on the metaphase plate, if we lined up our chromosomes, our homologous chromosomes, so that all the recessives were on one side and all the dominance were on the other, these would be the gametes that would result. If we set it up where the dominant was on one side and the recessive other one was on the same size, I don't even know if you can imagine that, but I can, we could end up with something like this or something like this. Do you agree with that? If that hurts your brain, if you can't get there, go back, rewatch the meiosis lecture and draw a picture of meiosis with chromosomes and have these alleles labeled, because it's really interesting to do that. These are all the possible, we can't have any other possible gametes with a T and a P in each gamete. Same genotype, we're going to end up with the same possible gametes over here. And again, the order does not matter. Now it's our next task. We're going to make our punnett square, squares are cool, you thought squares were lame, no, squares are cool. So now all I'm going to do is I'm going to put my gametes into a square, but now I just have way more gametes to deal with, right? This is a little P. T, big P, T, little P, these are just my gametes. Big P, can you see why your bookkeeping is actually really important? Yeah, I can. Holy dihybrid cross. If we cross these two, we're going to end up with, now here's another bookkeeping trick. For me, I look at this and I go, oh, I have to put my T's together and I have to put my P's together just so I can read it easily. Doesn't matter, but you will be happier if you do it that way. And then what is the, like, what does this guy look like? That guy is tall and purple. And I don't know how to write it. It's purple and I guess we'll make tall green just so you can visualize the phenotypes. So one of our possible phenotypes is going to be tall green. And then let's see what's this guy going to look like. This guy is going to also be tall and green. And so, hmm, maybe I'll, yeah, I'll just do it this way. What's this guy going to look like? Tall green. What's this guy going to look like? Tall green. All of those are tall green. Let's see if we can go until we find something that's not tall green. Tall green. Tall, not green. I'll do it in, I don't know what color this is. Well, that's yellow. I do know what yellow looks like. Look, whoa, you cannot see that, can you? Okay, fine, I'll make it orange. That's a lovely color of orange. That is not tall green. That is tall green. What are we talking about, green? Green is purple. What, this is tall purple, right? This is tall white. You knew what I meant all along, didn't you? I'm almost done with this lecture, so I'm not changing it because you know exactly what I mean. Now, we only have one tall white so far. We have five tall purples. Hmm, the green color messed me up, didn't it? Okay, you finish filling it out and you tell me the phenotypic ratio of a dihybrid cross. You will have to do these in lab. I'm sure we'll have one in lecture, so make sure that you are comfortable with doing this. You're a rock star, then we'll check ourselves when we come back. All right, have fun, heredity rocks. Bye, bye.