recombine

Recombine refers to the process of combining or rearranging components to form a new arrangement. In biology, genetic recombination is a fundamental mechanism that reshuffles genetic material to create diversity and to repair DNA. It occurs in various contexts, including sexual reproduction, DNA repair, and genome evolution.

Major forms of genetic recombination include homologous recombination, site-specific recombination, and non-homologous end joining. Homologous recombination uses stretches of similar DNA sequence to guide exchange, often producing crossovers between homologous chromosomes during meiosis and generating recombinant chromatids. Enzymes such as RecA in bacteria and Rad51 in eukaryotes mediate strand invasion and exchange, with intermediate structures like Holliday junctions that are later resolved. Site-specific recombination relies on recombinases that recognize defined DNA sequences to produce targeted insertions, deletions, or inversions; Cre-loxP and Flp-FRT are well-known systems used in genetic engineering. Non-homologous end joining repairs double-strand breaks by directly ligating ends, which can introduce insertions or deletions and is important for maintaining genome integrity despite being error-prone.

Recombination also occurs in viruses, where RNA recombination can arise through template switching during replication, leading to recombinant genomes that can affect viral properties and evolution.

In biotechnology, recombination-based systems are exploited to manipulate DNA, create conditional alleles, study gene function, or generate libraries of variants. The term “recombine” thus encompasses both natural genetic processes and engineered applications that generate new genetic or molecular combinations.