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Home Q & A Board Biology-Related Homework Help Genetics and Developmental Biology
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ask4help ask4help
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11 years ago
A. If two parents with normal vision have a colorblind son, what are the parents genotypes?

B. What are the chances that their daughter will be colorblind?
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smmrwdssmmrwds
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11 years ago
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11 years ago
A.  The father with normal vision is hemizygous, since he only has one X and has a normal allele on his X chromosome.  Therefore, the colorblindness allele must have come from the mother and since she has normal vision, then she must be heterozygous.  If C is the normal allele and c is the colorblindness alleles, then the cross is:

mother  X(C)X(c)  x  X(C)Y  father

children possibilities (all in equal proportions):

X(C)X(C), normal female
X(C)X(c), carrier female
X(C)Y, normal male
X(c)Y, colorblind male

B.  0%, all of the female offspring will have normal vision, but half of the females will be carriers (heterozygotes).
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