Question

"I don't want to have any daughters who are colorblind like me!"

Awilda and Frank at Breakfast
Awilda: Are you sure you want to wear that new shirt to work today? A green and red shirt like that would be better for Christmas, not for St. Patrick's Day
Frank: Oh no! I really thought this shirt was just different shades of green. Wheres Not again! the red?

Frank: We should try to find a way to make sure we only have sons, no daughters. I dont want
Awilda: Remember, the doctor said that he doesn't think that any of our children will be
Frank: I don't see how he can be so sure about that. I'm colorblind, so some of our children
Awilda: The doctor said that, since no one in my family was colorblind, I almost certainly do not
Frank: That doesn't make any sense. Neither of my parents is colorblind, but I'm color to have any daughters who might be colorblind like me. Color blindness would be a big problem for a girl. colorblind should be colorblind like me. have the allele for colorblindness, so none of our children will be colorblind. think that our children will be more likely to be colorblind since they will have a colorblind father.


What are the genotypes of Frank and Awilda? (Since the allele for color blindness is located XO_ See on the X chromosome, use the symbol X for an X chromosome with the recessive allele for color blindness and X for an X chromosome with the dominant allele for normal color vision. The Y chromosome does not have this gene, so it is represented by Y.)

Answer 1

Frank's genotype is XoY since he's colorblind, and Awilda's genotype is XX because she has no family history of color blindness. Sons of Frank and Awilda have a 50% chance of being colorblind while it's impossible for their daughters to be colorblind, but they may be carriers.

Step-by-step explanation:

The genotypes of Frank and Awilda can be determined based on the inheritance patterns of color blindness, which is an X-linked recessive trait. Since Frank is colorblind and male, his genotype must be XoY. Awilda, not being colorblind and having no family history of colorblindness, is likely to have a normal genotype of XX. If Awilda had a colorblindness gene, she would be a carrier with genotype XoX, but it is suggested that she doesn't carry the trait at all due to her family history. Therefore, it is incorrect to assert that males can be carriers of red-green color blindness, as it is X-linked recessive, not autosomal dominant.

To have a daughter who is colorblind, both parents must contribute an X chromosome with the recessive colorblind gene. In Frank and Awilda's case, since Frank has an affected X chromosome but Awilda has two normal X chromosomes, their sons have a 50% chance of being colorblind (inheriting Frank's Xo), while their daughters cannot be colorblind—they can only be carriers if they inherit Frank's Xo chromosome.