Genetics

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.
Genetic recombination is the process by which two DNA molecules exchange genetic information, resulting in the production of a new combination of alleles. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on to progeny. Most recombination is naturally occurring. During meiosis in eukaryotes, genetic recombination involves the pairing of homologous chromosomes. This may be followed by information exchange between the chromosomes. The information exchange 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 pathway in Figure); or by the breaking and rejoining of DNAstrands, 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 alleles are not produced since the sister chromosomes are usually identical. In meiosis and mitosis, recombination occurs between similar molecules (homologs) of DNA. 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.

Genetic recombination and recombinational DNA repair also occurs in bacteria and archaea.

Recombination can be artificially induced in laboratory (in vitro) settings, producing recombinant DNA for purposes including vaccinedevelopment.

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 pathogens.