Genetic recombination 158005 201906930 2008-03-29T22:22:32Z 129.67.52.92 '''Genetic recombination''' is the process by which a strand of genetic material (usually [[DNA]]; but can also be [[RNA]]) is broken and then joined to a different DNA molecule. In [[eukaryotes]] recombination commonly occurs during [[meiosis]] as [[chromosomal crossover]] between paired chromosomes. This process leads to offspring having different combinations of genes from their parents and can produce new chimeric [[alleles]]. In evolutionary biology this shuffling of genes is thought to have many advantages, including that of allowing sexually reproducing organisms to avoid [[Muller's ratchet]]. In [[molecular biology]] "recombination" can also refer to artificial and deliberate recombination of disparate pieces of DNA, often from different organisms, creating what is called [[recombinant DNA]]. [[Enzyme]]s called ''[[recombinases]]'' [[Catalysis|catalyze]] natural recombination reactions. [[RecA]], the recombinase found in [[Escherichia coli|E. coli]], is responsible for the repair of DNA double strand breaks (DSBs). In yeast and other [[eukaryote|eukaryotic]] organisms there are two recombinases required for repairing DSBs. The [[RAD51]] protein is required for [[Mitosis|mitotic]] and [[Meiosis|meiotic]] recombination and the [[DMC1 (protein)|DMC1]] protein is specific to meiotic recombination. ==Chromosomal crossover== {{main|Chromosomal crossover}} [[Image:Morgan crossover 1.jpg|thumb|Thomas Hunt Morgan's illustration of crossing over (1916)]] '''Chromosomal crossover''' refers to recombination between the paired [[chromosome]]s inherited from each of one's parents, generally occurring during [[meiosis]]. During [[Meiosis#Prophase I|prophase I]] the four available [[chromatid]]s are in tight formation with one another. While in this formation, [[homology (biology)|homologous]] sites on two chromatids can mesh with one another, and may exchange genetic information. Because recombination can occur with small probability at any location along chromosome, the [[recombination frequency|frequency of recombination]] between two locations depends on their distance. Therefore, for genes sufficiently distant on the same chromosome the amount of crossover is high enough to destroy the correlation between [[alleles]]. ==Gene Conversion== {{main|Gene conversion}} In gene conversion, a section of genetic material is copied from one chromosome to another, but leaves the donating chromosome unchanged. ==Nonhomologous recombination== {{main|Non-homologous end joining}} Recombination can occur between DNA sequences that contain no sequence [[homology (biology)|homology]]. This is referred to as ''Nonhomologous recombination'' or [[Non-homologous end joining|nonhomologous end joining]]. ==See also== *[[Recombination frequency]] *[[Recombination hotspot]] *[[Four Gamete Test]] ==External links== *[http://www.mun.ca/biochem/courses/3107/Lectures/Topics/Recombination_holliday.html The Holliday Model of Genetic Recombination] *{{MeshName|Genetic+recombination}} *[http://www.blackwellpublishing.com/trun/artwork/Animations/Recombination/recombination.html Animated guide to homologous recombination.] ==References== *Alberts, B. et al., ''Molecular Biology of the Cell'', 3rd Edition. Garland Publishing, 1994. {{NCBI-scienceprimer}} {{Genetic recombination}} [[Category:Cellular processes]] [[Category:Molecular genetics]] [[ar:تأشيب جيني]] [[de:Rekombination]] [[fr:Recombinaison génétique]] [[he:שחלוף]] [[nl:Recombinatie (genetica)]] [[ja:遺伝的組換え]] [[no:Rekombinasjon]] [[pl:Rekombinacja genetyczna]] [[ru:Рекомбинация (биология)]] [[fi:Rekombinaatio]] [[sv:Rekombination (biologi)]] [[uk:Генетична рекомбінація]] [[zh:遺傳重組]]