What is Chromosome inversion?
[[File:Inversion pericentrique.JPG|thumb|right|230px|A pericentric inversion is an inversion which includes the [[centromere]].]] [[Image:a_arm_inversion.jpg|thumb|right|230px|An inversion loop in a chromosome]] An '''inversion''' is a [[chromosome]] rearrangement out of [[mutation]]. In chromosome inversion, a segment of a chromosome is reversed end to end. An inversion is when the chromosome breaks at two points in a chromosome (or at the end) and does a 180 degree flip. The [[gene]]s inside the inversion are in the reverse of the original order. == Consequences == What matters is whether the inversion interferes with [[crossing-over]] during [[meiosis]]. Meiosis is the type of [[cell division]] which produces sex cells ([[gametes]]). === Both chromosomes the same === If both chromosomes of a pair have the same inversion, and there is no extra or missing genes, then there is no problem with meiosis. === Inversion on one chromosome only === When the homologous chromosomes pair in prophase I of [[meiosis]], the genes on the chromosomes pair up. The only way this can happen after an inversion is if the homologous pairs form a loop. If a [[cross-over]] occurs within this inversion loop, it can lead to loss or gain of [[DNA]]. For this reason, people with inversions in their germ cells often have lower [[fertility]]. This is because the gametes are damaged. Families that are carriers of inversions may be offered genetic counselling and testing.<ref>Gardner R.J.M. and Sutherland G.R. 2004. ''Chromosome abnormalities and genetic counseling''. Oxford.</ref> == References == {{Reflist}} [[Category:Chromosomes]]