A male and a female are each heterozygous for both cysti...

Question

A male and a female are each heterozygous for both cystic fibrosis (CF) and phenylketonuria (PKU). Both conditions are autosomal recessive, and they assort independently.

What proportion of the children will have either PKU or CF but not both?

Accepted Answer

Hi, everyone. Let's look at our next question. It says which of the following assertions about the independent assortment of two excellent recessive traits is true. Well, when we think about excellent traits, we know they must be on the X chromosomes. So if we have two X linked recessive traits, we know that both genes are on the same chromosome. And just like with autosomal traits, they might be linked if they are close together, they're definitely on the same chromosome, but they might assort independently if they're very far apart on the X chromosome. So it really depends on their position. So let's look at our answer choices and see which one is true. We do want to know that choice D is all of the above statements are true. So we have the possibility that all of our answers might be correct. So let's start looking through them. Choice. A says the two traits may show independent assortment or complete linkage depending on their position. Well, this is correct, depending on their position, they may be linked if they're closer together or as sort pretty much independently if they're far enough apart. So choice A is true. But since we have that possibility of more than one true statement, I'm not gonna pick it as my answer just yet to put a little dot Here to mark that it's correct. But wait and see what my other answer choices are. Choice B says the two traits always show complete linkage and do not assort independently. Well, this would not be correct um because they could have sorted independently if they're very far apart on the chromosome. Also, since choice B is incorrect, we can also rule out choice D, all of the above statements are true since choice B is not correct. So with that in mind, I on a test, I could go ahead and select a as my answer since I know I only have one correct answer and move on. But in the interest of thoroughness, we'll look at choice C choy C says the two traits always assort independently. Well, that's also definitely incorrect. They're on the same chromosome, the X chromosome. So there's a lot of chances that they'll be linked at least some of the time, although it's possible for them to assort independently. So choice C is not our answer. So we know that choice A must be our answer. Which of the following assertions about the independent assortment of two X linked recessive traits is true. And that's choice. A, the two traits may show independent assortment or complete linkage depending on their position. See you in the next video.

Struggling with Genetics?

A male and a female are each heterozygous for both cystic fibrosis (CF) and phenylketonuria (PKU). Both conditions are autosomal recessive, and they assort independently.

What proportion of the children will have either PKU or CF but not both?

Watch next

Understanding Independent Assortment practice set

Struggling with Genetics?

A male and a female are each heterozygous for both cystic fibrosis (CF) and phenylketonuria (PKU). Both conditions are autosomal recessive, and they assort independently.What proportion of the children will have either PKU or CF but not both?

Watch next

Understanding Independent Assortment practice set

A male and a female are each heterozygous for both cystic fibrosis (CF) and phenylketonuria (PKU). Both conditions are autosomal recessive, and they assort independently.

What proportion of the children will have either PKU or CF but not both?