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Homework Help: Autosomal and X-linked genetics problem!

  1. May 20, 2007 #1
    1. The problem statement, all variables and given/known data
    In the fruit fly drosophila melanogaster, vestigial (partially formed) wings (vg) are recessive to normal long wings (vg+) and the gene for this trait is autosomal. The gene for the white eye trait (w = white is recessive to w+ = red) is located on the X chromosome. Suppose a homozygous white-eyed, long winged female fly is crossed with a homozygous red-eyed, vestigial winged male.

    a) What will the genotypes and phenotypes of the F1 flies?

    b) What will the genotypes and phenotypes of the F2 flies?

    c) What will the genotypes and phenotypes of the the offspring of separate crosses of the F1 flies back to each appropriate parent?

    2. Relevant equations

    3. The attempt at a solution
    I know how to deal with autosomal and X linked trait questions individually but I don't know how to solve the question when both autosomal and X linked traits are involved.

    Help is appreciated. Thanks
  2. jcsd
  3. May 22, 2007 #2
    can someone please provide me some hints?
    I'm very stressed out about this question.
  4. May 23, 2007 #3


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    You set up the problem very much the same way as if it were autosomal or x-linked only. Try using a Punnet square to work it out as if it were any other autosomal two-trait cross, but use a symbol for the sex-linked traits that reminds you which chromosome they came from.
  5. May 25, 2007 #4
    Can you give me a few more hints or explanations?
    I'm still really confused.
  6. May 27, 2007 #5
    help please?
  7. May 29, 2007 #6
    If you know how to deal with them individually, you're going to be fine... remember the law of independent assortment?

    I think part of the problem is the very strange allelic naming system... the standard is to use the first letter of the dominant trait and for Capital letters to be dominant and lowercase letters to be recessive...
    ok other than that I think I can get you started without giving too much away: based on the information in the question I'd wager that the genotypes of the parents are: using W = Long Wing (w = recessive vetigial wing) and R=Red eye (r = recessive white eye) and remember Y=male
    we have a white eyes long winged female and we are told it is homozygous so: (WWrr) must be the genotype
    and red eyed vestigial winged male (also homozygous) must be (wwRY)
    simply do a dihybrid cross from there, and let us know if ya need some more help.
    Last edited: May 29, 2007
  8. May 29, 2007 #7


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    Thanks for jumping in Oaksinstructor. Sorry for not being able to get back sooner Intr3pid, I was away for a few days for the holiday. Yes, I think the unusual naming convention is causing added confusion...too many letters to get confused.
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