sex linked recessive

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biohelp22
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sex linked recessive

Post by biohelp22 » Mon Apr 24, 2006 9:01 pm

argghh

in humans , hemophilia is a sex-linked recessive trait. if a man and a woman produce a son who is a hemophiliac, which of the follownng must be true?

the father is a hemophiliac
both paretns carry the allele for hemphilia
neither parent carries the allele for hemophilia
the father carries the allele for hemophilia
the mother carries the allele for hemophilia

from what i can tell it would be the last choice since its recessive right?
help pweez
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LilKim
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Post by LilKim » Mon Apr 24, 2006 10:38 pm

hmm??? I too am puzzled.

Is it possible that more than one answer is correct??

I'm thinking A is most correct (but D is also correct???)

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Post by d00d » Tue Apr 25, 2006 3:41 am

or missing information perhaps?
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Post by kiekyon » Tue Apr 25, 2006 7:00 am

LilKim wrote:hmm??? I too am puzzled.

Is it possible that more than one answer is correct??

I'm thinking A is most correct (but D is also correct???)


no, hemophilia is passed down from mother to son.

so, the answer should be E

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LilKim
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Post by LilKim » Tue Apr 25, 2006 2:22 pm

oh ok...I guess I've always assumed that whenever a question says "sex-linked" it always refered to Y-linked inheritance .... Cuz don't they usually say "X" linked instead of "sex-linked" in cases when an affected allele is linked to the X?

I guess, I don't remember the nomenclature?? Or maybe we we were supposed to know that hemophilia is passed from mother to son?

I dunno... i'm tired!

thats kool though.. thanks!

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Khaiy
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Post by Khaiy » Tue Apr 25, 2006 6:42 pm

I've almost always seen sex linked in reference to the X chromosome, since so many more sex linked issues can appear on the X chromosome. But technically sex linked means any allele that occurs just on one sex chromosome. But yes, the answer is E (this is a classical example for sex linkage brought up in virtually any genetics class).

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Poison
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Post by Poison » Tue Apr 25, 2006 9:03 pm

The mother must carry.
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Genetics

Post by atypical10 » Mon Jun 05, 2006 11:42 pm

I think It the answer might be that the father carries the allele for hemophillia.

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MrMistery
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Post by MrMistery » Tue Jun 06, 2006 5:37 pm

No, the mother must be a carrier. Check out criss-cross transmition of sex-linked characteristics. Or do a punnet square :D
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Poison
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Re: Genetics

Post by Poison » Wed Jun 07, 2006 2:03 pm

atypical10 wrote:I think It the answer might be that the father carries the allele for hemophillia.

Father can not be a "carrier", he can only be hemophiliac if he has the gene.
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MrMistery
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Post by MrMistery » Wed Jun 07, 2006 5:24 pm

maybe he has Klwinefelter :lol:
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Post by svetliau » Wed Jun 07, 2006 6:31 pm

I am quite sure that the mother carries hemophilia; the father cannot ever be a carrier because if he has the gene, he is sick. The father can be hemophiliac himself, but is has no effect on his son because the boy gets his X chromosome from the mother and the Y from the father and since the sick gene is placed on the X, E is the only correct answer.

N.B. Males can never be carries of hemophilia; they can be sick or healthy. There is no middle way here.
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