Dominant and rescessive question - (Sep/18/2010 )

Assume blue eyes result from a recessive mutation in a single gene. The dominant allele produces brown eyes. If the mother is blue-eyed and the father has brown eyes, what is the genotype of the father, if they have a child with blue eyes?
a)BB
b)Bb
c) Not enough information.

I want to know if b is the correct answer since I think c is the correct one when the instructor posted it on his powerpoiint. Thanks.

cbio on Sat Sep 18 20:21:04 2010 said:

The reason why b is the answer is as follows

blue eye is caused by a single recessive allele.

Mother has blue eyes thus her genotype is bb
Child has blue eyes thus child's genotype is bb
One allele is inherited from one parent. Thus the child has inherited one b allele from its mother and the 2nd b allele from its father.
Thus the father must have one b allele.

The allele for brown eyes is dominant. Thus the genotype for brown eye can be either BB or Bb.

Given that we know the father has a b allele and has brown eyes. He must have a Bb genotype