- The trading of fragments of genetic material between chromosomes before the egg and sperm cells are created. Key features of recombination include the point-to-point association of paired chromosomes (synapsis) followed by the visible exchange of segments (crossing over) at X-shaped crosspoints (chiasmata). Recombination is the principal way of creating genetic diversity between generations. By shuffling the genetic deck of cards, recombination ensures that children are dealt a different genetic hand than their parents.
* * *1. The process of reuniting of parts that had become separated. 2. The reversal of coupling phase in meiosis as gauged by the resulting phenotype. SEE ALSO: recombinant. 3. The formation of new combinations of genes.- genetic r. 1. the presence in progeny of combinations of genotypes and perhaps phenotypes, not present in either parent, resulting from crossing-over; 2. in microbial genetics, the inclusion of a chromosomal part or extrachromosomal element of one microbial strain in the chromosome of another; the interchange of chromosomal parts or genes between different microbial strains.- homologous r. the exchange of corresponding stretches of DNA between two sister chromosomes.- site-specific r. integration of foreign DNA into a particular site in the host genome.
* * *re·com·bi·na·tion .rē-.käm-bə-'nā-shən n the formation by the processes of crossing-over and independent assortment of new combinations of genes in progeny that did not occur in the parentsre·com·bi·na·tion·al -shnəl, -shən-əl adj
* * *re·com·bi·na·tion (re″kom-bĭ-naґshən) 1. the reunion, in the same or a different arrangement, of formerly united elements which have become separated. 2. in genetics, the process that creates new combinations of genes by shuffling the linear order of the DNA, such as occurs naturally by crossing over of homologous chromosomes during meiosis or of homologous DNA sequences in somatic cells during mitosis, or occurs in vitro when DNA or RNA is manipulated for genetic engineering.
Medical dictionary. 2011.