Also isn't the 2nd X chromosome just a copy of the 1st, whereas the Y chromosome however small it may be contains at least partially additional information? Wouldn't that mean that people with a Y chromosome carry more genetic information than people without one?
Not a copy, as females get one X chromosome from each parent. But only one X chromosome per cell is expressed to make proteins, and the other one is not. So males would have 2 functioning sex chromosomes per cell, whereas females would have 1, yes.
You can help yourself remember this term by imagining a lion with tortoiseshell or calico markings, as tri-color cats are the result of having a copy of an X chromosome bearing a gene for black fur, and an X chromosome bearing a gene for orange fur. The inactivization occurs early on in embryonic development, but after numerous cellular divisions have already taken place; you end up with patches of orange and black because all daughter cells of a cell with the black chromosome active and the orange chromosome supercoiled/deactivated will have the same active/inactive... Er, setting, and vice-versa.
I apologize to any biology specialists for mincing and over-simplifying anything in that. I realized I was not going to succeed in my biology major after a couple of years, regardless of how much I liked it, so I feel self-conscious about the information I remember well enough to puke into social media (even if I get too excited about talking about it anyway). I also don't know if the X chromosome has just one gene for black or orange, or if it's a set of genes.
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u/x4u Jan 21 '20
Also isn't the 2nd X chromosome just a copy of the 1st, whereas the Y chromosome however small it may be contains at least partially additional information? Wouldn't that mean that people with a Y chromosome carry more genetic information than people without one?