Basic meiosis question

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dae
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Basic meiosis question

Post by dae » Mon Mar 09, 2009 8:48 pm

In metaphase I can both of the chromatids of a double chromosome crossover? In textbooks the tetrad complex is always shown laid flat (it looks like XX ) so it makes since that only one chromatid from each double chromosome would be able to recombine in that geometry. But if this is a simplification for the sake of 2D display and the tetrad complex can actually assemble so that one double chromosome lays on top of the other (I can think of any reason they couldn't) than it makes sense that both chromatids could cross over.

Does anyone know the actual geometry of metaphase I?

Thanks!

plasmodesmata11
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Post by plasmodesmata11 » Tue Mar 10, 2009 1:06 am

The chromosomes do synapse as if the X's were on top of each other. I guess in your book the diagrams are simplified.

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MrMistery
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Post by MrMistery » Tue Mar 10, 2009 3:53 am

during a crossover 2,3 or 4 strands can cross over.
See the figures in this book http://books.google.com/books?id=3E_0H6 ... #PPA193,M1
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dae
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Re: Basic meiosis question

Post by dae » Tue Mar 10, 2009 4:07 am

Thanks! that makes way more sense :-)

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