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'''Crossover''' is a term used in [[genetics]] to describe the process where two [[chromosome|chromosomes]] exchange segments of their [[DNA]] during [[meiosis]]. This process leads to the production of [[gamete|gametes]] with different combinations of [[gene|genes]] than either parent, contributing to [[genetic variation]].

== Process ==

The process of crossover occurs during the prophase I stage of meiosis, specifically during the [[pachytene]] substage. The [[chromosome|chromosomes]] align themselves along their lengths and exchange segments of [[DNA]]. This exchange is facilitated by the formation of a [[synaptonemal complex]], a protein structure that binds the chromosomes together.

The points at which the DNA is broken and rejoined are known as [[chiasma|chiasmata]]. The formation of chiasmata is a complex process that involves several [[enzyme|enzymes]], including [[endonuclease]]s, which cut the DNA, and [[ligase|ligases]], which rejoin the cut ends.

== Consequences ==

Crossover has several important consequences. Firstly, it generates [[genetic variation]], which is crucial for [[evolution]]. By shuffling the genes between chromosomes, crossover creates new combinations of genes, which can lead to new [[trait|traits]] and potentially beneficial adaptations.

Secondly, crossover ensures the correct segregation of chromosomes during meiosis. The chiasmata hold the chromosomes together until they are ready to be pulled apart during [[anaphase]]. This prevents the chromosomes from being randomly distributed to the daughter cells, which could lead to [[aneuploidy]], a condition where cells have an abnormal number of chromosomes.

== See also ==

* [[Genetic recombination]]
* [[Meiosis]]
* [[Chromosome]]
* [[DNA]]

== References ==

<references />

[[Category:Genetics]]
[[Category:Cell biology]]
[[Category:Evolution]]

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Crossover - Revision history

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