Codominance & Blood Type

by Jason Amores Sumpter
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in this video, we're going to talk about co dominance as it relates to human blood type. And so it turns out that blood type in humans is a common and classic example of co dominance. And so, of course, we introduce co dominance in our last lesson. Video. Now blood type in humans is determined by combinations of three possible a leal's, which are capital I, a capital I B or lower case I. And so all combinations of these three alleles are possible for the Gina type. Now the capital I A and capital I be a leal's are actually the ones that air code dominant to each other. And that means that the capital I A does not dominate over the capital. I be in the capital. I b does not dominate over the capital I A. So they do not mask each other, and instead they're going to both be equally expressed in patches whenever you have Ah, hetero psycho with both of these a Leal's. However, the lower case, I Khalil, is recess it to the other two a Leal's Capital I A and Capital High B. And so if we take a look at our example down below at the A B O blood types notice that we have this chart here with three columns. The first column represents the Gina type. The second column represents the surface molecules that air found on the red blood cells themselves. And the third and final column represents the final phenotype or the blood type that the individual would actually have. And so notice that here in the first row of the genotype, what we have is capital a capital I A. So to a leal's for capital I A or we have one capital. I am one lower case I and again recall that the lower case I is recess it to the capital I A which means that Onley Capital I A would be expressed. And so either of these Gina types, either this one or this one, would lead to Onley a molecules on the surface of the red blood cell. Kind of like what you see over here a red blood cell right here, surrounded by these a molecules on the surface. And that, of course, would mean that this person would be a type a blood. Now the next row, what we have is capital. I be capital I b or capital. I be lower case I. And again, the lower case I is recess. If to the capital I be so on Lee, the capital I b is gonna be expressed here in this genotype. But both of these Gina types here would lead to Onley be molecules on the surface of the red blood cell. So it would look like this red blood cell here with these be molecules on the surface. And of course, that would mean that this individual would have type be blood. Now, when an individual has one capital I A and one capital, I be together. Um, the these two a Leo's are co dominant to each other, And so that means that neither of them are going to dominate or mask the other. Instead, they're both going to dominate together, and they're both gonna be equally expressed. And so in that case, you get both A and B molecules equally expressed in patches on the surface of the red blood cell. And so again, here we have the red blood cell. But notice that we have patches of a and be on the surface of this red blood cell and these patches, and neither of them dominate over the other. Instead, they're both equally being expressed on the surface, and that is a classic example of co dominance. And so, of course, this person here would have a blood type of A B. They would have a B blood. And then last but not least, the final Gina type is having to lower case eyes. And an individual that has to lower case eyes is not going to have either, uh, molecule A or molecule B on the surface. And so instead, they're going to basically have, uh, a red blood cell that has neither a or B uh, blood. And so instead, they're going to have type o blood. And you could think that the, uh oh is almost like the naked look here of the type O blood without any surface molecules on its surface. And so this year concludes our introduction to co dominance and blood type, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video