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barr body and colorblindess

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

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barr body and colorblindess

Postby Mikau16 » Thu Oct 25, 2007 1:07 am

I can't quite get this problem. I think because i'm not exactly sure what barr body in males is.

A married couple, both of whom have normal vision, produced a colorblind son. Examination of cell samples showed the presence of a Barr body. What is the probable genotype of the son with respect to sex chromosomes and color blindness? What is the simplest explanation which will account for this genotype? (colorblindness is a sex linked recessive disorder)

what does it mean to say the kid has a barr body and what does that imply?
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Postby Jammerz » Thu Oct 25, 2007 4:47 am

If there are two or more X chromosomes, one of them will be inactivated and will be seen as a Barr body...

a normal male should have genotype XY, therefore, NO barr bodies. An abnormal male with Klinefelter's syndrome will have genotype XXY, accounting for the presence of a barr body.

If the son is to be colorblind then, he needs to have TWO faulty X chromosomes. Where do you think these X chromosomes with the recessive colorblindness trait came from?
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Postby mith » Thu Oct 25, 2007 6:20 am

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Accepting hardships as the pathway to peace;
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Postby Ultrashogun » Sat Oct 27, 2007 11:53 am

mith wrote:http://en.wikipedia.org/wiki/Triple_X_syndrome


Dont forget that it is in fact a son.
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