crossing over

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stancaris
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crossing over

Postby stancaris » Thu Apr 24, 2014 10:30 am

My question follows: On the average what percentage of genes on a chromosome cross over onto its homologous partner during meiosis? I read on the internet that it could be anywhere from 0 to 50% , but what would be the average percentage of crossovers? Would it be 25% or what?

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Pan Zareta
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Re: crossing over

Postby Pan Zareta » Sun Apr 27, 2014 2:24 pm

"[T]he internet" per se is not a source and crossing over (recombination) rates are usually expressed in terms of centiMorgan (cM) length rather than percentage of "genes" involved since recombination may occur within a "gene" sequence. A cM is a variable unit of distance between two loci on a chromosome within which there is a 1% chance of a recombination event occurring in a single generation. If you're looking for info re. recombination rates in the domestic horse, "...recombination rates vary widely across the genome....[o]n average..1cM is equal to 1 megabase (Mb)" ref. Swinburne & Lindgren, Chapt. 2 Equine Genomics (Chowdhary, 2013).