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by gus_massa
4432 days ago
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Some (maybe most) of the genes in the Y are only useful for men. Others of the genes in the Y chromosome are “vital”, but the X chromosome has a copy of them. So the men have two copies of these parts. In women, one of the X chromosomes is inactivated, so it’s almost like that each cell has only one (active) X chromosome. The shared part is not inactivated. So both men and women have two active copies of these parts, and only one active copy of the not shared parts. Read: http://en.wikipedia.org/wiki/X-inactivation More specifically: http://en.wikipedia.org/wiki/X-inactivation#Expressed_genes_... |
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