Synapsis is an event that occurs during meiosis in which homologous chromosomes pair with their counterparts and remain bound due to the exchange of genetic information. During meiosis, homologous chromosomes are paired and then separated to reduce the genetic content of the resulting gamete cells. Synapsis does not occur during mitosis, because homologous chromosomes do not pair with their counterparts. Synapsis starts when proteins connecting the various chromosomes to the nuclear membrane start to migrate. The proteins move around until their counterpart is found, and the synaptonemal complex is formed. The synaptonemal complex consists of protein and RNA, and hold the homologous chromosomes together.
Function of Synapsis
The synapsis of homologous chromosomes has a couple different functions in organisms. First, it holds the homologous chromosomes together through metaphase I of meiosis I, which allows them to be aligned on the metaphase plate and separated. This is a key task during meiosis, as this is how the genetic information in each gamete is reduced. Secondly, it allows homologous chromosomes to exchange information through crossing over. Crossing over occurs when similar portions of homologous chromosomes exchange position. This can redistribute how alleles interact with each other in the resulting organism. Synapsis ensures that alleles contained in these regions can be distributed independently of their parental source.