Purple Eye Make Up-What percentage of the daughters will have forked bristles and purple eyes?

by WhiteCreekPhotography

Question by Dulce: What percentage of the daughters will have forked bristles and purple eyes?
In Drosophila, the recessive allele for forked bristles is sex-linked and the recessive allele for purple eyes is autosomal. The wild-type alleles are for straight bristles and red eyes, respectively. A female, heterozygous for both pairs of alleles, is mated with a male with forked bristles and purple eyes. What percentage of the daughters will have forked bristles and purple eyes?

Best answer:

Answer by changudada
the genotype of the mother since she is heterozygous will be XBXbPp
of the father will be XbYpp
the gametes of the mother will segregate as XBP XBp XbP Xbp
while that of the father will be Xbp and Yp (lets ignore the Yp sice we are only interested in daughters)

thus the 4 possible combinations are XBXbPp (heterozygous for both thus straight bristles and red eyes)
XBXbpp (heterozygous for straight bristles and homozygous recessive for purple eyes)
XbXbPp (homozygous recessice for forked bristles and heterozygous for red eyes)
XbXbpp (homozygous recessive for both forked bristles and purple eyes)
the ratio is 1:1:1:1
therefore, there are 25% chances for any of the above combinations to occur, thus 25% of the daughters will be forked bristles and purple eyed

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