Crossover

This article is about biological crossover. For crossover in genetic algorithms, see Crossover (genetic algorithm).

Crossover is the process by which two chromosomes paired up during prophase I of meiosis exchange a distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and connect to each other's ends. If they break at the same locus, this merely results in an exchange of genes. This is the normal way in which crossover occurs. If they break at different loci, the result is a duplication of genes on one chromosome and a deletion on the other. If they break on opposite sides of the centromere, this results in one chromosome being lost during cell division.

Any pair of homologous chromosomes may be expected to cross over three or four times during meiosis. This aids evolution by increasing independent assortment, and reducing the genetic linkage between genes on the same chromosome.

See also: genetic recombination

A crossover may also refer to a particular type of electronic filter.

Music is said to crossover when it has commercial success in a genre other than that it was originally aimed at, or in multiple genres; see crossover music.

The term crossover is sometimes referred to when a character from one work of fiction appears in an other work of fiction, usually be a different author. Both the DC Universe and the Marvel Universe were originally built with crossovers between various superheroes.

See also: fictional crossovers

See Poobala.com's Crossover Spin-Offs Master Page for an extensive list of TV crossovers and shared realities.