A sex-linked recessive allele b produces a red-green colorblindness in people. A

Question

A sex-linked recessive allele b produces a red-green colorblindness in people. A normal woman whose father was colorblind has children with a colorblind man. a. Draw a pedigree of this situation. b. What genotypes are possible for the mother of the colorblind father? c. What are the chances that the first child from this couple will be a colorblind boy? Justify your answer. d. Of the girls produced by these parents, what proportion can be expected to be colorblind? Justify your answer by showing a Punnett square.

Explanation / Answer

Ans-A- affected male* unaffected female

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F1 Unaffected female * affected male

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F2 3unaffected male or female and 1 affected male or female.

Ans-B- the possible genotype of mother of colorblind father may be BB, BB or bb.

Ans-c- the possibilities of first child to be a colorblind boy is 25 percent. As there is equal chances of a child to be a boy or girl as well colorblind or not colorblind.

Ans-D- the proportions will be as follows.

Female gametes Bb, father's gametes- bb

25percent proportion.

B b B BB Bb b Bb bb

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