Sex linked recessive mutation

[darkryder341]

Hey guys,

I'm not exactly sure what 'sex linked recessive mutation' means.

Well, I know it means that the mutation is on the specified sex (in this case, it's associated with the male). But I just...don't really know how to figure out this one report sheet.

Basically, we bred fruit flies (P1 cross was wild type females x mutant white eyes males - wild type being dominant). These sheets we have to do are hypothetical, however.

So, here we have it:

The hypothetical cross: Wild type female x Mutant (white eyes) with sex-linked recessive mutation.

I'm trying to figure out what key symbols to use, first. I've been using W and w for the keys, but they switch with each hypothesis.

So, in this case, would W=wild type and w=mutant allele?

And if that's so, I'm not sure what the genotypes should be....

Sorry to bug you all, I'm just confused by the meaning of what sex-linked recess. is.

Thanks for any help!

[JackBean]

You can use any letters, you like
As is it sex linked, let's use X for X chromosome and Y for Y chromosome So, in this case, Y is WT and y is mutant
You have WT females, these have only X chromosomes (XX) and mutant males, which must be Xy in that case. Or is it vice versain Drosophila?

[darkryder341]

The species of fruit fly is Drosophila melanogaster, if that helps. But yes, I'm pretty sure you have it right. Females would be XX and males would be Xy. But I'm still not sure if I understand what the keys would be. Using Y, wild type = Y (dominant), and mutant = y (recessive)? Sorry if I'm being confusing xDD Would it help if I scanned the sheet so you can see what I mean?

And thanks for helping ^^

[JackBean]

I think, that not needed.
Well, as I said, female can be only XX, female, because he's mutant, must be Xy, that are the genotypes and now just do the Punnet square

..| X | y
..--------
X | ? | ?
X | ? | ?

[jeennyjeon]

if the wild type female is heterozygous (but is phenotypically "wild") then it would be X^H X^h (the carrots meaning superscripts). If the wild type female is homozygous for wild, then it would be X^H X^H.

The male mutant is X^h Y (the X chromosome holds the gene for the mutation and because that trait is recessive, it is a lowercase h).

so cross (X^H X^h) x (X^h Y)
and cross (X^H X^H) x (X^h Y)
and tadaaaaa

[jwalin]

jack bean
you are stealing my posts