There are two places of recombination, actually considered to be called homologous recombination, that occur, which are in the different prokaryotic and eukaryotic cells.
In eukaryotic cells, recombination occurs when two chromosomes, during meiosis, exchange two non-sister chromatids. In prokaryotic cells, DNA may be separated during division. Basically, in both cases of prokaryotic and eukaryotic cells, recombination involves the reciprocal exchange of DNA.To be more specific with homologous recombination, here is a more in-depth explanation of the steps of homologous recombination.
Two homologous DNA molecules, begin the process of crossing over.
An enzyme, called endonuclease, will create a break in one strand of each of the homologous DNA molecules.
The two halves of the broken DNA strands will then cross over, called a strand invasion, and immediately base pair with the opposite DNA strand and are bonded together with DNA ligase.
The cross over is complete and, because of the slightly different DNA formations, the newly formed DNA molecules are called heteroduplexes.
This process of recombination was proposed by the Holliday Model, composed by Robin Holliday 30 years ago. The other model, called the Meselson-Radding Model, was proposed by Charles Radding and Mathew Meselson after the Holliday Model inspired them. The difference between the Meselson-Radding Model and Holliday Model is there is only one strand invasion, unlike in the Holliday Model where there are 2 present strand invasions, and the other strand is, instead, duplicated to junction the two DNA molecules during cross over.
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were fully composed, as well as altered images and diagrams, by Josh Eisma (2002), unless otherwise specified.
