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General Biology

Learn the toughest concepts covered in Biology1&2 with step-by-step video tutorials and practice problems by world-class tutors

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13. Mendelian Genetics

Genotype vs. Phenotype

1
concept

Dominant vs. Recessive Alleles

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in this video, we're going to begin our lesson on Gina type versus phenotype. But before we can define genotype and phenotype, its first helpful to distinguish between the dominant and recessive a Leal's and so recall from our previous lesson videos that Ah Leal's are really just different versions of specific genes. And it turns out that a Leal's can be either dominant or recess ivo. And so the dominant ah Leo, as its name implies, is going to be in a Lille that dominates and exerts its effects whenever it is present. And so the dominant Khalil is usually symbolized with a capital letter. Now the recess. Ivo A. Leo, on the other hand, is, as its name implies, recess if I've meaning that it's going to have no effect if a dominant Khalil is present. And so the recess of Alil can Onley have its effect when there is no dominant Alil? And so the recess of Leo is symbolized using a lower case letter. Now, as Gregor Mendel was studying these P plants, what he realized is that the alil for Yellow piece was actually dominant to the olio for Greenpeace. And so this, of course, means that the yellow Khalil was going to be the dominant olio and the green Khalil is going to be the recess. Ivo Alil. And so if we take a look at our image down below, we can better distinguish between dominant and recessive a Leal's. And so notice over here we're showing you that the dominant Alil here is gonna be represented using a capital letter. And so here we're using the capital letter. Why? To represent the dominant Eliel for yellow pea color. And so you can see here that this dominant Alil really looks pretty dominant here in this image with these large muscles and the recess of Alil over here, on the other hand, is represented using lower case letters. So we have the lower case letter. Why? And the recess of Alil is not going to be dominant. It is not going to exert its effect if a dominant Khalil is present. And so you can see that the recess of the Leo here is kind of looking afraid of the dominant Alil. And again, the recess of a Leo here would be the polio for green pea color. And so what will notice moving forward is that the dominant Alil here is going to mask or hide the effect of the recess of Alil whenever the dominant Khalil is present. And so this here concludes our introduction to the difference between dominant and recessive alleles and will be able to get some more practice applying these concepts as we move forward in our course, and in our next video, we'll talk more about the difference between genotype and phenotype, so I'll see you all there.
2
Problem

An allele that exerts its effects whenever it is present is:

3
concept

Genotype & Phenotype

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So now that we've distinguished between the dominant and the recess of a Leal's in our last lesson video in this video, we're going to distinguish between the Gina type and the FINA type. And so the Gina type, as its name implies with the root gene in it, is going to be the Jeanette IQ combination of a Leal's in an individual organism. And so, in deployed organisms that have two copies of every gene or to a Leal's, the genotype is always going to be written as a pair of letters. Now there are Homo zegas Gina types, and there are also hetero zegas Gina types. Now the root homo is a route that means the same. And so it's no surprise that Homo zegas Gina types are going to be organisms that have two identical Ah Leal's for the same exact gene. And so the genotype could have two identical dominant alleles, or to capital wise. Or the genotype could have two identical recess Ivo Leal's or to lower case wise. And so the two capital wise that are identical here would be Homo Zegas dominant, and the two lower case wise that are identical would be Hamas, I guess. Recess it And we distinguish between those down below in our image. Now, the hetero zegas Gina type the root hetero, uh means different. And so it's no surprise that hetero zegas gina types are gonna be individuals that have two different ah Leal's for the same gene. And so, for example, having a dominant Khalil and a recess of alil those air two different Jalil's would create a hetero, zegas Gina type. And so, if we take a look at our image down below, notice that the left column here has the Gina type, the combination of a Leal's and an individual, and so notice that the first to the numbers one and two here correspond with the number one and two down below. Uh, they are referring to Homo zegas Gina types, meaning that the individual has two identical a Leal's. Now the top one here is referring to a Homo Zegas dominant Gina type because it has two capital wise too dominant a leal's and notice that the individual down here with the homo Zegas has a homo zegas recess Ivo Gina type because it has to lower case wise or to recessive a Leal's. And then, of course, this third Gina type that we have down here has one dominant Khalil and one recess of Alil, one capital y and one lower case. Why? Which means that it has two different alleles for the same gene. And it is going to be, ah, hetero zegas Gina type. And so again, the Gina type is always gonna be written as a pair of letters. It's the genetic combination of a Leal's. But what is that exactly is the phenotype? Well, the FINA type, as its name implies with the pH here in front of it, is going to be the physically expressed trait that results from the Gina type. And so the phenotype is going to be a physical expression of the gene, a type. And so it is going to be physically expressed in this scenario as either the yellow color of the P or the green color of the P, and so you can see down below. In our chart, we have the phenotype over here on the right column and noticed that the Hamas egas dominant Gina type leads to a yellow color FINA type. Notice that the Homa zegas recess Ivo Gina type leads to a green color phenotype and noticed that the hetero zegas Gina type leads to a yellow color FINA type. And so the reason that the hetero zegas uh, Gina type leads to a yellow color and not a grain color is because again, the dominant Alil will dominate and exert its effect over the recess of Alil when they're both together. And the recess of Alil is going to be masked when it's in the presence of the dominant olio. And so the dominant Leo is going to dominate and create a P with yellow color. And so just by visually looking at the color of these peas, we would not be able to distinguish between, uh, the Homo Zegas dominant and the hetero zegas Pete because they both have yellow colored peas. And so we would not be able to visually distinguish between them. However, there are ways that we can test to see what the Gina type is of plants that have these specific FINA types, and we'll get to talk more about that later in our course. But for now, this year concludes our lesson on the difference between the Gina type and the phenotype. How the genotype is a genetic combination of wheels or a pair of letters, whereas the phenotype is gonna be a physically expressed cherry such as the color of a specific people. And so we'll be able to get some practice as we move forward in our course, So I'll see you all in our next video.
4
Problem

If the two alleles for a particular gene are identical the gene pair is:

5
Problem

Mendel’s pea plants can have yellow peas or green peas. Mendel found the yellow pea color allele to be dominant over the green pea color allele. What does this mean?

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