I thought this type of recombination (essentially crossing over) happened because of the segregation of the homologous chromosomes in meiosis I. This doesn't happen in mitosis, so how is recombination possible?
Excellent Video. "It's a non-mutational event to loss of the good copy of... ." I have a question: In a scientific vision, Isn't the Crossing Over considered a mutation?
I see what you are getting at... when I refer to a mutation I mean a point mutation/insertion mutation or deletion mutation of one or a few of base pairs. When I refer to a cross-over event I am referring to the wholesale switching of hundreds of thousands of base pairs between two chromosomes. I know what you are saying and yes all of the above make changes to the genome. But the discussion, mutation events are considered to occur randomly and the chance of its occurrence at both alleles is low considering the size of the genome, however the cross-over of chromosomes affects much larger tracks of DNA - and leads to loss of both copies of an allele upon segregation (LOH). This effectively leads to a higher rate of loosing both good copies of a tumour suppressor gene.
If you are referring to Gene Conversion then I think this is another mechanism causing a single mutation to be propagated to both alleles. This is a seperate mechanism to Mitotic recombination, typically its one or the other leading to LOH (not both).
