Meiosis prophase I crossover

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gs99
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Meiosis prophase I crossover

Post by gs99 » Fri Mar 07, 2014 9:23 pm

“Chromosomal crossover (or crossing over) is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes.”
http://en.wikipedia.org/wiki/Chromosomal_crossover

Question: Due to the multiple layers of winding, how can parts of the chromosome break evenly?
Is it possible that the winding mechanism provides chiasma (break) points in advance? Like “tear along this line”?

Perhaps a chromosome has many segments of multiple wound layers (B and C) with a simpler connection material (xx) between them. The connection material is not visible to current microscopes due to its size compared to the chromosome mass.

Code: Select all

BBBBBBBxxBBBBBBBxxBBBBBBBxxBBBBBBBxxBBBBBBB
CCCCCCCxxCCCCCCCxxCCCCCCCxxCCCCCCCxxCCCCCCC

Where the chromatids overlap, specialist proteins break the segments. There could be other proteins that “hold” the two chromatids in place at the chiasma while this occurs.

Code: Select all

 
                        hhhhhhhhhhhhh
BBBBBBBxxBBBBBBBxxBBBBBBBx        xBBBBBBBxxBBBBBBB
CCCCCCCxxCCCCCCCxxCCCCCCCx        xCCCCCCCxxCCCCCCC
                        hhhhhhhhhhhhh

The specialist proteins re-attach the segments to the target chromatids:

Code: Select all

BBBBBBBxxBBBBBBBxxBBBBBBBxxCCCCCCCxxCCCCCCC     
CCCCCCCxxCCCCCCCxxCCCCCCCxxBBBBBBBxxBBBBBBB         

They can then report: A crossover has been completed.

Considering the evidence of real images and normal occurrence of crossovers, that’s my prediction.

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