location of chromosomal cross over

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tucki
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location of chromosomal cross over

Post by tucki » Mon May 07, 2007 6:55 am

Where do the chiasma of chromosomal crossovers occur? Are they mostly random or mostly induced?

I briefly read of crossover-hotspot-instigator (chi) sequences, which encourage crossover at those points, and also that crossovers were some how linked to protein complexes associated with synasis.

is there any information or hypothesis around suggesting that any crossover inducers, would occur at the borders of gene sequences such that only the whole genes are recombined? recombination by crossing over random sequences would mostly likely form deleterious mutants reducing the number of viable gametes (an evolutionary disadvantage)

ttp://post.queensu.ca/~forsdyke/chi01.htm
ttp://www.ncbi.nlm.nih.gov/entrez/query ... t=Abstract

siroma
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Re: location of chromosomal cross over

Post by siroma » Wed Jul 04, 2007 2:07 am

tucki wrote:
is there any information or hypothesis around suggesting that any crossover inducers, would occur at the borders of gene sequences such that only the whole genes are recombined? recombination by crossing over random sequences would mostly likely form deleterious mutants reducing the number of viable gametes (an evolutionary disadvantage)



1. Borders of genes are very subtle definition if we remember that eukaryotes have alot of non-coding dna including introns.
2. If you randomly finger at a locus of dna of higher eukaryotes, it's unlikely that you fall onto a gene, again, because of non-coding dna and introns.

I attached table with percentages of ncDNA vs cDNA for various organisms.

3. Why does CO need to cause deleterous mutation? It will cause gene conversion if Halliday junction is located in gene.
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