Incomplete Dominance vs. Codominance

in this video, we're going to begin our lesson on incomplete dominance vs co dominance, and we're gonna start off by introducing incomplete dominance in this video and then later, in a separate video, will introduce co dominance. And so in complete dominance is a pattern of inheritance where hetero Zegas individuals show a blended FINA type that is really just an intermediate of the FINA types, from the to a Leal's. And so in this example, what we're gonna look at is in complete dominance and red and white flour cross and how this incomplete dominance ends up making pink baby flowers. And so, over here, on the left hand side, what we have is this little table of the specific alil and the phenotype that they lied to. And really there are only two a leal's. In this example. There is the R one Alil, which leads to a red flower phenotype. And then there is an R to a Leo, which leads to a white flour phenotype. But notice that there is not a third Alil here within complete dominance. There's only two alleles, one for red flowers and one for white flowers. And so when we perform a cross fertilization of a red flower with a white flour notice. The red flower is homo zegas for the R one a little and the white flour is hedgerows. I'm sorry, Homo zegas for the r two alil. When we perform this cross here, what we end up getting our hetero zegas individuals we get are one and our two in each of these boxes. So we get a hetero zegas individuals, uh, for the R one and r two Lille and again remember the R one A little says make red flower and the are Tulio says make white flour. However, when we have a hetero zegas individual, it shows a blended phenotype that is an intermediate of the FINA types from the two alleles. So instead of getting red flower or ah, white flour with the Hedorah zag individual, we get a pink flower and notice that neither the are one nor the are to, Khalil says, make pink flower. They both, they either say make red flower or make white flour, but within complete dominance. We get neither red flower nor white flowers. Instead, we get intermediate blend of pink flowers, and that is the pattern of inheritance that's referred to as incomplete dominance, characterized by a blended phenotype that is an intermediate of FINA types. And so this year concludes our introduction to incomplete dominance and will be able to compare this to co dominance in our next video, so I'll see you all there.

in this video, we're going to introduce co dominance. And so co dominance is a pattern of inheritance, where hetero zygotes with two different Leal's equally express both FINA types from each alil in patches. And so, in other words, co dominance is when two different alleles dominate together. And really, when you take a look at the word co dominance, the Root Co. In front of co dominance is a route that means together, just like cooperate has The Root Co. Which means together. And SoCo dominance means that they're going to dominate together, where one alil does not mask the expression of the other Lille. Instead, they dominate together. And so we're going to take a look at an example of co dominance and red and white flowers. And so it's very, very similar to our last example in our last lesson video. Except instead of showing an incomplete dominance pattern of inheritance here we're showing a co dominance patterns of inheritance. And so once again, we're taking a look at these. Two different alleles are one Lille, which eyes gonna be associated with a red flower phenotype, and the are to Leo, which is associated with a white flour phenotype. Now when we cross a ho mose, I guess red flower with to our One on wheels and a home ozai Ghous White Flour with two are to a Leal's. We're going to get this pundit square that we see here where we get our one and our two hetero zygotes as the offspring. Just like what we saw in our last lesson video. But the difference was that within complete dominance in our last lesson video, the hetero zygotes would create some kind of blended intermediate phenotype. Uh, that did not really exist in either of the parents, however, here, with co dominance, there's no blended intermediate phenotype. There's no pink flowers. Instead, with co dominance, both FINA types are going to be equally expressed. So you see patches of white flour down below, and you also see patches of red flower. And so the white and red portions of this flower are expressed equally in patches, and that is what co dominance is all about. And this is in hetero zygotes that have one are one and one are two Leo. And so hopefully this year helps you better distinguish between incomplete dominance and co dominance. But in our next lesson video, we're going to introduce one of the most common examples of co dominance, which is blood type, so I'll see you all in that video.

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