genetics probability problem

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dolimitless
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genetics probability problem

Post by dolimitless » Fri Oct 10, 2008 4:01 am

In humans, the gene for the type of hairline an individual has is controlled by a single autosomal gene and the allele for having a widow's peak is dominant to the allele that causes the lack of a widow's peak.
A) Two heterozygous parents have a daughter that has a widow's peak, What is the probability that their second child will be a boy who lacks a widow's peak?
B) What is the probability that this couple will have three daughters in a row who all lack widow's peaks and then a son who has a widow's peak?

my teacher says my answer is wrong, can anyone help me?

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mith
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Post by mith » Fri Oct 10, 2008 4:56 am

what's your answer?
Living one day at a time;
Enjoying one moment at a time;
Accepting hardships as the pathway to peace;
~Niebuhr

lostincyberspace
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Re: genetics probability problem

Post by lostincyberspace » Sat Oct 11, 2008 4:53 pm

Remember that the chance of having a male or a female is 1/2. In an autosomal dominant disorder, don't forget that the affected person can be either homozygous dominant (WW) or heterozygous (Ww), and the person lacking the disorder will be homozygous recessive (ww). Make a punnett square to determine probability for the hairlines.

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