Is a daughters X-Chromosome identical to the mum's X?

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

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kechel
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Is a daughters X-Chromosome identical to the mum's X?

Post by kechel » Sun Aug 08, 2010 7:52 am

Hi everybody,

I have a question about X/Y-Chromosomes in human genetics and evolution:

Are the X/Y-Chromosomes severely changed (so except little mutations), remixed or rebuild within a human compared to his parents?
So I mean, is the X-Chromosome I got from my mother more or less exactly the same that my childrens receive? Or is the X-Chromosome my childrens receive some mix, made up from the X & Y combination?
Or is the whole X/Y-Chromosome stuff only a stupid (schoolisch?) simplification and cannot applied like this?

Here is an example to clarify (and to show up some implications):

Example:

Grandpa 1
X1 & Y1
Grandma 2
X2 & X3
-> Mum 3 gehts X1 & X3

Grandpa 4
X4 & Y2
Grandma 5
X5 & X6
-> Dad 6 gets Y2 & X5

Daughter 7 gehts e.g. X1 & X5 -> so actually has no genes from grandma 2 and no genes from grandpa 4 ?
Son 8 gehts e.g. X3 & Y2 -> actually has no genes from grandpa 1 and no genes from grandma 5 ?

Thanks for your thoughts!

Darby
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Post by Darby » Sun Aug 08, 2010 8:08 pm

Your example is right, I think, except that it only applies to the genes on the X, and there are 22 other chromosomes to consider - Grandpa 1 and grandma 5 make contributions elsewhere.

There may be modifications of chromosomes, such as methylations, that cause the passed X's to behave differently than before. Not sure that has been seen in sex chromosomes, though.

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JackBean
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Post by JackBean » Tue Aug 10, 2010 6:53 am

Well, basically you're right, but the two Xs should recombine as well. And also, I think there is/are some region/s at Y chromosome, which is able to recombine with X, however, very small probably
http://en.wikipedia.org/wiki/Y_chromoso ... inhibition
kolean could know more.

However, as Darby pointed out, you should not forget the other 22 pairs of chromosomes, which can be freely combined ;)
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

kechel
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Re: Is a daughters X-Chromosome identical to the mum's X?

Post by kechel » Tue Aug 10, 2010 5:16 pm

Perfect! Thanks for the replies!

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