The accompanying pedigree shows the transmission of albi...

Question

The accompanying pedigree shows the transmission of albinism (absence of skin pigment) in a human family.

Using allelic symbols of your choice, identify the genotypes of the male and his two mates in generation I.

Accepted Answer

Hi, everyone. Welcome back. Let's look at our next question. It says muscular dystrophy is an excellent recessive condition. If the father is affected by this genetic condition, how will it affect their offspring? Well, a really important thing to note when we look at our answer choices is that all of our answer choices refer to the possibility of Children, boys, girls or all Children being affected. In this case, that means affected by the condition, having muscular dystrophy. We're looking at a recessive condition. Um In that case, the choices aren't just not having the gene or being affected by the disease. You could be hetero ziggy's and be a carrier, someone who doesn't have the disease but carries an allele and can potentially pass it on. But that's not what our answers are asking us about. They're just asking about whether the Children will be affected by the disease. So that's important to keep in mind here. So let's look at our punnett square to think about which Children, if any will be inherited muscular dystrophy from their father and be affected by the disease. So I'm going to put up a Punnett square here. Just a simple four square pendant square. Since we're just talking about the X chromosomes across the top, I'm going to put the father's sex chromosomes. So one ex the father is affected by muscular dystrophy. So I'm going to give it a superscript m to represent the allele, the gene for muscular dystrophy. And then the other one is a Y chromosome. Then down the left side will be the mother's sex chromosomes. The mother's presumably unaffected and not a carrier. So just to unaffected X chromosomes on the left side. So when we look at the offspring, we see on the left side where we have the female offspring who inherit an X from either parent, you've got a normal X from the mother, an X M from the father and same on the bottom, normal extra mother X M from the father. The father has only one X chromosome. So that's the only one he can pass on to the female offspring. When we look at the male offspring on the right side, well, they do not inherit the X chromosome from the father. So they will never inherit the allele. For muscular dystrophy, they inherit a normal X from their mother and a Y chromosome from their father. With the result that males are unaffected, they do not have the disease. They also are not carriers, they can't be carriers, they only have only one X chromosome, but they have no alil obviously for muscular dystrophy, when we look at the female offspring on the left side while the females are going to be carriers, they are headed for the muscular dystrophy gene. Um but they are not affected by muscular dystrophy because they only have one allele for the disorder and it's a recessive condition. So, since our answer choices are asking us which Children will be affected, the answer is none of the Children will be affected, male or female. The females are carriers but none of the Children will actually have muscular dystrophy. So let's look for our answer choices and we see that indeed. Choice D is none of the offspring will get affected. All of our other answer choices. Choice. A all Children will get affected be all boys will get affected. See all girls will get affected, refer to Children inheriting muscular dystrophy and having the condition which none will. So A B and C all incorrect. Our answer here is choice D none of the offspring will get affected. See you in the next video.

The accompanying pedigree shows the transmission of albinism (absence of skin pigment) in a human family.

Using allelic symbols of your choice, identify the genotypes of the male and his two mates in generation I.

Key Concepts

Pedigree Analysis

Genotype vs. Phenotype

Allelic Symbols

Watch next

The accompanying pedigree shows the transmission of albinism (absence of skin pigment) in a human family.Using allelic symbols of your choice, identify the genotypes of the male and his two mates in generation I.

Key Concepts

Pedigree Analysis

Genotype vs. Phenotype

Allelic Symbols

Watch next

The accompanying pedigree shows the transmission of albinism (absence of skin pigment) in a human family.

Using allelic symbols of your choice, identify the genotypes of the male and his two mates in generation I.