So now that we've covered the law of segregation in our last lesson video, in this video, we're going to talk about Gregor Mendel's second law, which is the law of independent assortment. Now recall that way back in our previous lesson videos when we talked about meiosis, we introduced independent assortment. And so recall from those older lesson videos that independent assortment is when homologous chromosomes independently and randomly align themselves on the metaphase 1 plate during meiosis 1. And this is going to create a large amount of genetic diversity in the gametes and in individual organisms. Gregor Mendel's law of independent assortment basically says that allele segregation of one gene does not affect the allele segregation of another gene. And this is because these genes are found on different pairs of homologous chromosomes. The law of independent assortment essentially allows for gametes with all possible combinations of alleles from different genes. And we'll be able to see that down below once we wrap up this explanation. Now Gregor Mendel was able to come up with this law of independent assortment by monitoring the inheritance of multiple genes at once to make this discovery using what are known as dihybrid crosses. And we'll talk a lot more about dihybrid crosses later in our course, but for now, you should just know that dihybrid crosses allowed Gregor Mendel to determine this law of independent assortment.
If we take a look at our example image below, what we're showing you is independent assortment that occurs during metaphase 1 of meiosis 1. Again, independent assortment occurs during metaphase 1 of meiosis 1. Notice that over here on the left-hand side and over here on the right-hand side, we're showing you two possibilities of metaphase 1 during meiosis 1. Here this is representing meiosis 1, more specifically metaphase 1 of meiosis 1. During metaphase 1 of meiosis 1, homologous chromosomes are going to align themselves on the metaphase 1 plate. There are different possible alignments for these homologous chromosomes, and that's why we have possibility 1 and possibility 2 shown here. Possibility number 1 shows the red chromosomes lined up on the left-hand side and the blue chromosomes lined up on the right-hand side. Whereas, possibility number 2 shows one of the blue chromosomes on the left, the other blue chromosome on the right, one of the red chromosomes on the left, and one of the red chromosomes on the right. These are different possibilities for the alignment of these homologous chromosomes. And because each of these possibilities is equally likely during meiosis 1, that is what the law of independent assortment is all about.
What you'll notice here is that we've got two pairs of homologous chromosomes. We've got the larger pair of homologous chromosomes at the top and a smaller pair of homologous chromosomes at the bottom. Notice that the larger pair of homologous chromosomes contains the color gene. The color gene has different alleles. It has different versions of the gene. It has the capital Y version of the color gene which says yellow color and then it has the lowercase y version of the color gene which says green color, green peas. Then we have the smaller pair of homologous chromosomes containing a different gene, the shape gene. The shape gene also has different alleles. It has the capital R allele, which is for a rounded shape of the pea, and then it has a lowercase r version of the gene, a lowercase allele version of the gene, which basically says make a wrinkled pea, a wrinkled-shaped pea. And so what you'll notice is that the yellow bands over here represent the yellow allele, and the green bands represent the green allele. The blue bands here represent the capital R round allele, and the orange bands here represent the lowercase r wrinkled allele. Again, you can see how the alignment of these alleles, and the alignment of these chromosomes, is going to lead to different possibilities in the gametes. And because of the law of independent assortment and the segregation of one gene does not affect the segregation of the other gene, it allows for gametes with all combinations of alleles from different genes, which means that we can have a yellow round peas or a yellow wrinkled pea, or we could have a green round pea or a green wrinkled peas because of independent assortment. You can see that we have our yellow round peas over here, represented here, our green wrinkled peas represented here, our green round peas represented here, and our yellow wrinkled peas represented here. And so, again, it's because of the law of independent assortment creating these different possibilities that allows for all of these different combinations that we see down below. This once again refers to the law of independent assortment, how these homologous chromosomes, how they align on this metaphase 1 plate is independent and random from each other. And so this here concludes our brief introduction to the law of independent assortment and we'll be able to get some applying these concepts as we move forward in our course. So I'll see you all in our next video.