 Now let's look at the concept of independent assortment. Independent assortment essentially is something that happens during metaphase one because homologous chromosomes line up on the metaphase plate randomly. Now take a look. All I've done is shown you two different pairs of chromosomes. You've got one homologous pair at the top and one homologous pair at the bottom. I've shown you that these homologs contain different genes. So these are literally different chromosomes, but we've got one from mom and one from dad. Each pair has one chromosome from mom and one chromosome from dad, and we've got some genetic diversity with the alleles that came from mom and the alleles that came from dad. You can also see that we're going to go through metaphase one, and so actually crossing over has already happened because that happens in prophase one. So now look at how I lined up my homologs, and this is random. So it's a flip of a coin how they're going to line up. It just so happens that I lined them up so that there was a big green on one side but the little green is on the other side. So you can visualize after metaphase one what happens. Homologs split, so look at what happens when my homologs split in anaphase one. I'm going to end up with two cells. These are my two cells, and they're different. We've got one red and one green in each cell, and it is different. Like think about the big green one. We've got different possible alleles in that set up in that cell as opposed to the big red one. So what's going to happen in, if this were, let's say, metaphase two and we're going to split our sisters, let's go ahead and go through anaphase two where we split our sisters. And now you have four possible gametes. Here's one gamete, here's another gamete, and here's another gamete, and here's another gamete. And I think I'm going to make it so that you can see that those gametes, now I'm just making them small so that we can keep track of them and put them somewhere. But you can see that these are the arrangements, these are the resulting gametes from the original set up with a green and a red lined up on each side. All right, watch and be amazed. Here's some little sperms with sperm tails. This was my lineup. This is how they lined up on the metaphase plate. These were the gametes that resulted. We could line them up differently. If we are dealing with just two chromosomes, two different chromosomes, two homologous pairs, there's two ways we can line up on the metaphase plate. We could line up with all green on one side and all red on the other. And then go through anaphase, split our homologues. Now go through anaphase two, split our sisters. And now look at my gametes. Look at how now my gametes either have all green or all red. And this is just dealing with two possible gametes. So look at this. There are my cells. Here was my lineup. This is how they lined up. Do you remember how the first ones lined up? They lined up differently. Independent assortment means that my homologous pairs line up on the metaphase plate in a random order. You want to know something crazy? I'll tell you. We have what, 23 pairs of homologs? 23 pairs of homologs can line up eight million different ways. And then we can do like the crazy statistics, math, probability, madness that my brain can't even begin to comprehend. But if I do that math madness, it's like two to the 23rd power. It's eight million different ways we could line up. So you could have chromosome one from mom on this side and everything else from dad on the other. And then you could have chromosome two on this side from mom and everything else from dad in the other. What? There's eight million different ways you could line them up. That blows my mind. And each one of those different ways just from independent assortment will result in a different kid. Think about your siblings. I think about my kids. Like, dude, you can't get much more different than those two boys are. And they came from the same genetics. Like they have all the same opportunities, same mom, same dad. And they're like, whoa, you can have fraternal twins that have such different genetics. They can be different colors. They can have different. I mean, it's like, wow, unbelievable diversity. Okay, I'm going to show you a picture of the other way we can get diversity of critters from this whole thing. And we'll blow our mind even more and then we'll do a summary.