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independent assortment

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independent assortment

Postby leeroykincaid » Fri Apr 12, 2013 7:28 am

Whenever independent assortment is mentioned, it's in the context of meiosis I.
However, if crossing over occurs, sister chromatids are no longer identical so diversity should be increased during meiosis II because of independent assortment of chromosomes in metaphase II, conserning the recombinant and non-recombinant sister chromatids.
Am I right or is there more to this story?
Why is this never mentioned in textbooks?

Thanx in advance
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Postby JackBean » Thu Apr 18, 2013 8:08 am

You're right, but the meiosis II cannot increase the diversity because it plays with given cards.
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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Re:

Postby leeroykincaid » Tue Apr 23, 2013 8:40 am

JackBean wrote:You're right, but the meiosis II cannot increase the diversity because it plays with given cards.


Well, yes, it's much more complicated than my simplification primary reason being different rates of crossing over occuring in meiosis I in each of the cells and the fact that each of the cells is already different because of the independent segregation in anaphase I.
If crossing over was exactly the same in every cell in meiosis I and there was no independent segregation, then we could draw a simple analogy between segregation of homologous chromosomes in anaphase I and separation of recombinant and non-recombinant chromatid in anaphase II.

Being as it is, we could still compare the separation of chromatids with another shuffling of the dealt cards.
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