Ihe kachasị na-ahụkarị nke crossover chromosomal bụ homologous recombination, ebe chromosomes abụọ ahụ na-ekerịta usoro yiri nke ahụ. Non-homologous recombination nwere ike imerụ mkpụrụ ndụ, ebe ọ nwere ike imepụta chromosomal translocations na mkpụrụ ndụ ihe nketa abnormalities. The recombination mmeghachi omume na-catalyzed site enzymes mara dị ka recombinases, dị ka RAD51. Nzọụkwụ mbụ na recombination bụ a abụọ-n'ịghaghachi kpatara ma ọ bụ site na a nuclease ma ọ bụ n'ebe ọdịda anyanwụ ọgwụgwụ nke DNA. A usoro nke recombinations nwekwara ike na-etinye aka na mmezi DNA, karịsịa na cell si nzaghachi abụọ-ụdọ breaks.
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