Skip to main content
Pearson+ LogoPearson+ Logo
Start typing, then use the up and down arrows to select an option from the list.


Learn the toughest concepts covered in biology with step-by-step video tutorials and practice problems by world-class tutors

3. Extensions to Mendelian Inheritance

Understanding Independent Assortment


Gamete Genetics and Independent Assortment

Play a video:
Was this helpful?
Hi in this video, we're gonna be talking about independent assortment. So this is a short topic, but I made it its own separate thing because it is so important that you understand this um one of Mendel's postulates or laws or whatever you want to say, because you're going to get a lot of questions that start with something like assuming dandelion inheritance or assuming jeans are a sorting independently. And essentially what that's talking about is this slaw right here. So even though it's a short topic, it's super important. And so the independent assortment is mental, second law. So you may see it as that and pretty much what it does, what it states is that a wheels of two genes assort independently. And so as soon as you understand what that means, it makes complete sense. But sometimes this definition can be a little confusing. And so what we typically do is we perform a di hybrid cross to look at two genes and the offspring that making those two genes between two organisms produce. And so the really important thing here is realizing that independent assortment is focusing on more than one gene. Um in this case it's usually defined as two. But it can be more than that, right? It can be as many genes as you want, but just knowing that each gene assort independently. So what is a sorting independently mean over this, we have, I'm going to do an example. So for this type we have a genotype, A BB. So A will say it's for yellow and B is for shape. So we have two genes, one is affecting color and one is affecting shape. So gene A. Does color and gene be the shape. Now when we um So what does it mean A sorting independently? Well it's talking about gamete formation. Remember gametes are the sex cells, these are the sperm or the egg. So if we were to ask what's the genotype of the gametes whenever you produce this this is the gametes are telling you whether or not the genes are sorting independently. So we have these two genes A. And be both of them have two different alleles. So if they assort independently meaning that each gene or each allele is going to its own gammy independent of the other genes in one of our gametes. Well the first thing we focus on is the first gene. So that's one A big A. And a little A. And because there's two sets we just repeat this. So each gamete gets one A. A little either the big A. Or the little A. And because there's four we just you know they double it so to get big A's. And to get little ace then because the genes are sorting independently, that means that we can now do the second gene which is G. B. And we do the same thing. Let me actually change the color here. So we can really see it A B. Little b. And um so now what are the next to before we just repeated it. But this time we have to do it backwards. And the reason we have to do it backwards is because we want this gammy which has two uppercase letters to be different than this gamma. Which has the upper case A. In the lower case B. Now this is an example of a sorting independently. So it's not that these two are always seen together. If it was a sorting non independently, that would mean that the A. And the B. Always work together. The uppercase A. And uppercase B. We're always together, the lower case A. And lower case B. We're always together because they would be together they would be what we're going to refer to as linked in the future. But we haven't talked about that yet. But for now just know that if it's a sorting independently, any combination of gametes can be made. It can be uppercase a. Lowercase B. Uppercase bow, lower case. Both. Any combination of the alleles can be made. If they're sorting independently. If they're not a sorting independently, then you can only get one combination that occurs. So hopefully that makes sense. So this right here is the example of independent assortment, this is what you're going to see or what they're going to try to get you to answer any time it starts out with. Like assuming dandelion inheritance or anything like that. This is the way that it's done is that the a. Alleles sort of go into their gametes completely independent of the B. Alleles. Then the B. Alleles come in. They do whatever they want. And if you have more little C. D. E. They all sore independently. They all go into their own gametes completely independent of the other alleles. So that's independent assortment. Let's now move on.

Which of the following gametes cannot be formed from the genotype AaBBCc?


Which of the following gametes cannot be formed from the genotype DDeeFfGG?


Which of the following gametes cannot be formed from the genotype HhJjKK?