13. Mendelian Genetics
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in this video, we're going to introduce pedigrees, and so a pedigree is a chart or family tree that depicts family relationships and pedigrees can be used to track ah phenotype over many generations. Now, within a pedigree, circles are going to represent females, whereas squares are going to represent males now, shaded or colored shapes are going to represent affected individuals that do have the phenotype of interest. And then horizontal lines that go from side to side are going to connect to mating parents, whereas vertical lines that go up and down are going to be used to connect parents to offspring. And so if we take a look at our example down below, we can get a better feel for these symbols and connections on a pedigree. And so notice that circles that are not shaded represent unaffected females, whereas squares that air unshaded represent unaffected males. Now, the shaded in circles and squares represent affected females and affected males respectively. And when we say affected, we mean that they actually have whatever FINA type it is that is off interest. Now when you see horizontal lines connecting to shapes, this represents mating parents, so this would be the mating for, um uh, male. And this would be the mating females Now down below. What you'll see is the vertical connections that you see will connect the parents to the offspring, which we have down below. And, of course, if these offspring are connected like what we see here, that means that they're going to be siblings coming from the same set of parents. And so, as we move forward in our course, will be able to talk Maura, Maura about pedigrees and how to read them. But for now, this is our brief introduction to the symbols on a pedigree, and I'll see you all in our next video.
How to Read Pedigrees
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in this video, we're going to talk a little bit mawr about how to read pedigrees. And so pedigrees air typically read from the top to the bottom by starting from the first generation. Now, in our example down below, we're going to use this pedigree over here to determine the relationships between the indicated individuals on the pedigree. And over here, what we have are the indicated individuals here, we're going to put the specific relationships. And again, over here we have the pedigree itself. Now the first set of shapes that we see at the very top represents the very first generation or the P generation, if you will. And so you can see that we have an unaffected male because it's an unshaded square mating with an affected female because it's a shaded circle. And then, of course, the next generation of organisms that we see here would be, uh, the F one generation, the first generation of Children. And then, of course, the generation below them would represent the F two generation or the generation that, uh, is going to be the Children of the F one generation. And so what? You'll notice here, eyes that person number one, uh, indicated here with the number one here. Eyes going to be person number fives, Father. And the reason for that is because there is a vertical connection between person one and person five. And that means that person five is the offspring of person one. And, of course, person one is a male. So that means that person one is going to be person fives, Father. Now moving on to the next one. We have person number seven, which is over here on person number four, which is over here are and which will notice here is that both of them are vertically connected to the same sets of parents. Which means that they are siblings to one another and more specifically because they're both females. They are sisters. So person seven in person for our sisters. And then last but not least, here we have person number 11, which is down here and person six, which is up here, and it says person number 11 is person Sixes, daughter. And the reason that we know that again is because there is a vertical connection between the two. So that means that, uh, they this will be the parents, and these will be the offspring. And, of course, 11 is a circle, which means that she is a female, so that means that she would be person sixes, daughter. And so really, this year concludes our example problem and we'll be able to get Mawr practice reading pedigrees as we move along through our course. But for now, this year concludes this video, and I'll see you all in our next one.
Additional resources for Pedigrees
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