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Q: Genetic Formula ( Answered 5 out of 5 stars,   1 Comment )
Subject: Genetic Formula
Category: Science > Biology
Asked by: jennifer1000-ga
List Price: $2.00
Posted: 06 Oct 2004 12:05 PDT
Expires: 05 Nov 2004 11:05 PST
Question ID: 411137
A colorblind man that has type AB blood marries a woman that can pick
out his ties for him no matter how colorful they are, even through her
dad was colorblind. His spouse is heterozygous for type B blood. If
they decided to spend over $250,000 and have a curtain climber, what
would be the chances of them having a son that would be colorblind and
also have type A blood?
Subject: Re: Genetic Formula
Answered By: librariankt-ga on 07 Oct 2004 07:20 PDT
Rated:5 out of 5 stars
Hi Jennifer,

The tricky part of this question is that colorblindness (red-green) is
recessive on the X chromosome, making it sex linked.  See this page
for a discussion of the genetcs:
 I'm calling our colorblind gene C and c, with the Y chromosome not
having either of them so noted just as Y.

Here are our parents' genetics:

Man: ABcY
Woman: BOCc (she is heterozygous because her father, who was cY, gave
her his colorblind X gene, but she's not colorblind so her other X
must have the dominant C)

In this case, since we have three different options for each gene
(A,B,O for blood; C, c, Y for colorblindedness), there are sixteen
different possible outcomes - which distinguishes us from our previous
questions.  Usually you'll have two possible ways to get a
heterozygous child - but in this case each possible combination has a
1/16th chance of showing up.

I.e., you have 1/16th chance of having a colorblind boy with type A blood.

If it helps, you have 1/2 chance of getting a boy.  There are four
blood types possible (AB, BB, BO, and AO), so you have a 1/4th chance
of type A blood.  Half of your boys will be colorblind.  Multiple the
probabilities: 1/2 times 1/4 times 1/2, and you get a 1/16th chance of
boy - AO - colorblind.

jennifer1000-ga rated this answer:5 out of 5 stars

Subject: Re: Genetic Formula
From: netbuster-ga on 06 Oct 2004 12:34 PDT
50 %

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