Genetics Problem II

[bionewbie]

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]

Draw you punnet square and results will include both proportion and sex of the offspring.

[bionewbie]

Yes, my problem is setting up the actual punnet squares ie what are the gametes when the traits are sex linked?

[Jennifer]

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

[Dr.Stein]

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?