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sex-influenced trait

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

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sex-influenced trait

Postby 09MillerLr » Tue Mar 14, 2006 10:16 pm

What is sex-influenced trait?? :D
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Postby Khaiy » Tue Mar 14, 2006 10:22 pm

Do you mean sex linked trait?

If so, it means that a particular phenotype is controlled by genes on a sex chromosome (X or Y).
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Postby kiekyon » Wed Mar 15, 2006 2:12 am

nope, they are different
sex influenced traits are traits controlled by autosome
sex linked is controlled by sex chromosome, x or y
but basicallly, they mean that the traits expression are different between male and female
one example of sex influenced trait is baldness
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Postby Khaiy » Wed Mar 15, 2006 3:28 am

I could be wrong, but I thought that baldness was sex linked. Because it's supposed to be passed down along your mother's side, that means that the baldness gene would have to be on the X chromosome, because that way a male would not have a working copy of the gene to compensate, and so baldness would occur. However, if a female were to recieve a baldness gene on the X chromosome from her father, and also from her mother, then she would experience hair thinning/loss.

Am I just way off?
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Postby kiekyon » Wed Mar 15, 2006 3:50 am

probably..
my understanding of sex influenced baldness
is if the gene are heterozygous Bb,
B will be dominant in males and recessive in females
hence, only heterozygous male display this trait
however BB men and women both will display baldness
nothing to associate with X or Y though
of course, i may be wrong
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Postby MrMistery » Wed Mar 15, 2006 6:16 pm

How many bald women have you seen? Personaly, i have not seen any. But i have a lot of bald men or men losing their hair(that will deffinetly be bald in the future). If it were true and the gene was located on an automose, it would have to have the same frequency in males and females, which is deffinetly not the case.
So, i agree with Khaiy. Recessive X-linked
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Postby Khaiy » Wed Mar 15, 2006 10:24 pm

I just double checked with my bio prof today, and kiekyon was right about the difference between sex linked and sex influenced traits, but baldness is a sex linked trait.
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Postby kiekyon » Thu Mar 16, 2006 1:52 am

MrMistery wrote:How many bald women have you seen? Personaly, i have not seen any. But i have a lot of bald men or men losing their hair(that will deffinetly be bald in the future). If it were true and the gene was located on an automose, it would have to have the same frequency in males and females, which is deffinetly not the case.
So, i agree with Khaiy. Recessive X-linked


The typical pattern of female pattern baldness is different from that of male pattern baldness. The hair thins all over the head, but the frontal hairline is maintained. There may be a moderate loss of hair on the crown, but this rarely progresses to total or near baldness as it may in men.
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Postby AlyHawthorne » Thu Mar 16, 2006 2:17 am

In woman, (using B and b as the alleles) B is actually the recessive trait and b (the gene for non-baldness) is the dominant trait. In men, it's reversed: B is the dominant trait and b is the recessive trait. So it's rarer for women to be bald, but it does happen.
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Postby February Beetle » Thu Mar 16, 2006 4:11 am

Also when women do have the balding gene it happens a lot later in life, when estrogen levels are lower, so the process starts after menopause, so it still takes time for them to get severley bald after that. I guess the high estrogen level keeps the baldness from happening? Sorry my bio teacher said this last semester, like I can remember that far!
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Postby kiekyon » Thu Mar 16, 2006 9:35 am

from wikipedia...

One of the identified genes involved in male pattern baldness is located on the X chromosome, which is inherited only from the maternal side in the case of men, but this one gene does not explain all the cases of male pattern baldness. Baldness in a child cannot be predicted only from the mother's lineage. There are probably other unidentified autosomal genes that are also involved. In other words, genetics does play a role in male pattern baldness, but the genes can come from either parent, not just the mother
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Postby MrMistery » Thu Mar 16, 2006 7:43 pm

Well, i was half right :))
Always good to learn new things...
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