## Genetics Problem II

Genetics as it applies to evolution, molecular biology, and medical aspects.

bionewbie
Coral
Posts: 113
Joined: Sun Nov 07, 2004 9:54 pm

### Genetics Problem II

In a cross between a white-eyed female fruit fly and a red-eyed male, what percentage of the femal offspring will have white eyes? (White eyes are X-linked, recessive).

How would the question be different if red eyes are dominant and X-linked? What would the expected phenotypes of the offspring?

canalon
Inland Taipan
Posts: 3909
Joined: Thu Feb 03, 2005 2:46 pm
Draw you punnet square and results will include both proportion and sex of the offspring.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

bionewbie
Coral
Posts: 113
Joined: Sun Nov 07, 2004 9:54 pm
Yes, my problem is setting up the actual punnet squares ie what are the gametes when the traits are sex linked?

Jennifer
Garter
Posts: 20
Joined: Mon Nov 28, 2005 10:16 pm
For sex-lined trait, X and Y are used to represent male and remale gametes. The male is only able to donate one version of the allele, for example:
Since white eyes are recessive, we can use rr to represent them. Since the male can only carry the one allele, we can use R for the dominant red eyes:

XrXr (Female) X XrY (Male)
XR Y
Xr XRXr XrY

Xr XRXr XrY
~*Jennifer*~

Dr.Stein
King Cobra
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Location: 55284 Yogyakarta, Indonesia
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### Re: Genetics Problem II

bionewbie wrote:In a cross between a white-eyed female fruit fly and a red-eyed male, what percentage of the femal offspring will have white eyes? (White eyes are X-linked, recessive).

How would the question be different if red eyes are dominant and X-linked? What would the expected phenotypes of the offspring?

I AM sure I already did this somewhere in this forum, but how could and where my post gone away?

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