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A man with normal vision marries a color-blind woman. Red-green color blindness is an X- linked recessive disorder. They have a daughter who has normal color vision. What is the probability that she is heterozygo

Respuesta :

Answer: The probability is 100%.

Explanation: The chromosome X is related to gender. A man carries two different chromosomes (XY) and a woman carries two similar chromosomes (XX). The offspring of a couple will inherited:

  • If it is a boy, he inherites the chromosome Y from his father and X from his mother;
  • If it a girl, she inherites X from her father and X from her mother;

In the question, the woman is color-blind, which means she carries the recessive alleles: [tex]X^{d}X^{d}[/tex]

The man, on the other hand, is normal, so his X-linked genotype will be: [tex]X^{D}Y[/tex].

Now, since they have a daughter, she inherited her double X from each of her parents, which means she inherited one [tex]X^{d}[/tex] from her mother and one [tex]X^{D}[/tex] from her father.

So, the daughter's genotype can only be heterozygotic  [tex]X^{D}[/tex][tex]X^{d}[/tex] in other words, the probability is 100%.

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