Editing Genetic recombination (section)

{{Short description|Production of offspring with combinations of traits that differ from those found in either parent}}
[[File:Homologous Recombination.jpg|thumb|400px|A model of meiotic recombination, initiated by a double-strand break or gap, followed by pairing with an homologous chromosome and strand invasion to initiate the recombinational repair process. Repair of the gap can lead to crossover (CO) or non-crossover (NCO) of the flanking regions. CO recombination is thought to occur by the Double Holliday Junction (DHJ) model, illustrated on the right. NCO recombinants are thought to occur primarily by the Synthesis Dependent Strand Annealing (SDSA) model, illustrated on the left. Most recombination events appear to be the SDSA type.]]
'''Genetic recombination''' (also known as '''genetic reshuffling''') is the exchange of [[DNA|genetic material]] between different [[organism]]s which leads to production of offspring with combinations of traits that differ from those found in either parent. In [[eukaryote]]s, genetic recombination during [[meiosis]] can lead to a novel set of [[genetics|genetic]] information that can be further passed on from [[parent]]s to offspring. Most recombination occurs naturally and can be classified into two types: (1) ''int<u>er</u>chromosomal'' recombination, occurring through independent assortment of [[allele]]s whose loci are on different but homologous chromosomes (random orientation of pairs of homologous chromosomes in meiosis I); & (2) ''int<u>ra</u>chromosomal'' recombination, occurring through crossing over.<ref>{{Cite journal |last1=Daly |first1=M J |last2=Minton |first2=K W |date=October 1995 |title=Interchromosomal recombination in the extremely radioresistant bacterium Deinococcus radiodurans. |journal=Journal of Bacteriology |volume=177 |issue=19 |pages=5495–5505 |doi=10.1128/jb.177.19.5495-5505.1995 |issn=0021-9193 |pmid=7559335|pmc=177357 }}</ref>

During [[meiosis]] in [[eukaryotes]], genetic recombination involves the pairing of [[homologous chromosome]]s. This may be followed by information transfer between the chromosomes. The information transfer may occur without physical exchange (a section of genetic material is copied from one chromosome to another, without the donating chromosome being changed) (see SDSA – Synthesis Dependent Strand Annealing pathway in Figure); or by the breaking and rejoining of [[DNA]] strands, which forms new molecules of DNA (see DHJ pathway in Figure).

Recombination may also occur during [[mitosis]] in eukaryotes where it ordinarily involves the two sister chromosomes formed after chromosomal replication. In this case, new combinations of [[allele]]s are not produced since the sister chromosomes are usually identical. In meiosis and mitosis, recombination occurs between similar molecules of [[DNA]] ([[homologous sequence]]s). In meiosis, non-sister homologous chromosomes pair with each other so that recombination characteristically occurs between non-sister homologues. In both meiotic and mitotic cells, recombination between homologous chromosomes is a common mechanism used in [[DNA repair]].

[[Gene conversion]] – the process during which homologous sequences are made identical also falls under genetic recombination.

Genetic recombination and recombinational [[DNA repair]] also occurs in [[bacteria]] and [[archaea]], which use [[asexual reproduction]].

Recombination can be artificially induced in laboratory (''in vitro'') settings, producing [[recombinant DNA]] for purposes including [[vaccine]] development.

[[V(D)J recombination]] in organisms with an [[adaptive immune system]] is a type of site-specific genetic recombination that helps immune cells rapidly diversify to recognize and adapt to new [[pathogen]]s.