Sex-Linked Inheritance

by Jason Amores Sumpter
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in this video, we're going to begin our lesson on sex linked inheritance and so recall from our previous lesson videos that the sex chromosomes include the X or the Y chromosome. And the sex chromosomes are gonna be the ones that actually determine the sex of the organism, whether the organism develops male reproductive systems or female reproductive systems. Now females are typically going to have two X chromosomes, whereas males, on the other hand, are going to typically have one X chromosome and one y chromosome. Now, sex linked genes are defined as genes that air found on either sex chromosome. So genes found on the X chromosome R X linked genes and genes found on the Y chromosome are. Why linked genes now? It's also important to note that the X chromosome is significantly larger than the Y chromosome, and we could tell just by comparing the number of genes on each chromosome. And so the X chromosome actually contained somewhere around 1100 X linked genes, which is a lot in comparison to the Y chromosome, which only contains about 100. Why linked genes and so again, just by comparing the number of genes you can see that the Y chromosome must be significantly smaller, since it has so many less genes than the X chromosome, which is gonna be significantly larger. And so, if we take a look at our image down below, over here on the left hand side, notice that we're focusing on sex linked genes and so you can see that here in red we are representing the X chromosome, which is significantly larger than the little Y chromosome that we have right next to it. And so the black band that you see right here represents an X linked gene because it represents a gene found on the X chromosome, whereas this band that you see over here on the Y chromosome represents a why linked gene now moving forward in our course were mainly gonna be focusing on the X linked genes and not so much on violent jeans. Now again, females tend to have two X chromosomes, as you can see here, and males, they tend tohave Onley, one X chromosome and one y chromosome. And so really, it's the presence of the why chromosome that's going to contain genes that allows for the male reproductive systems to develop now. What's also very important to note here in this video is that with each fertilization event, there's actually a 50% chance of having a female and a 50% chance of having a male. And so if we take a look at this pun it square that we have over here on the right hand side, which are notices that we're crossing a mother with a father. And again, females tend to have two X chromosomes, whereas males like the father tend have one X chromosome and one y chromosome. And so when my Asus occurs and these gametes are formed on, we complete the Pundits Square, which you'll notice is that in the offspring every time there's a 50% chance of having a female and a 50% chance of having a male. And so that is exactly what we're indicating here. A 50% chance of having a female with two X chromosomes right here and a 50% chance of having a male with one X and one y chromosome, as we see in these two possibilities. And so this year concludes our introduction to sex linked inheritance. But as we move forward in our course, we're going to continue to talk Mawr and Mawr about thes X linked genes and sex linked inheritance. So I'll see you all in our next video.