Question on X chromosome

Chris cs132 at york.ac.uk
Tue Dec 3 19:40:06 EST 1996


This is a question that no one at York university seems able to
answer.
The question is as follows:-

In females one X chromosome stays active and codes for proteins where
as the other chromosome is (supposedly) inactive and forms the dense
bar body which can be visibly seen under an optical microscope.

When females have 3 or more X chromoses 2 or more bar bodies
representing the inactive X's are visible.

Why do these women (especially in the case of 4 X,s) suffer from
physical and mental defects?

Are the inactive X,s truelly inactive?

Is it the fact that each cell of the body will express 1 of 3 or more
X  phenotypes instead of 1 of 2 (as it is random which X stays active
and which X's are domant).

Could it be the physical space the extra X's take up?

Or something entirely different.
				Chris Swainson




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