Meiosis

Abstract

Meiosis is the specialized type of cell division by which sexual organisms produce gametes. In most organisms, meiosis produces haploid gametes from diploid precursor cells. Meiosis halves the chromosome number via two successive rounds of chromosome segregation that follow a single round of chromosome replication. The first round of meiotic chromosome segregation is unique in that the sister chromatids remain associated while parental homologs (pairs of sisters) are segregated. As prerequisites for their segregation, homologs become intimately associated and connected by structures called chiasmata. Homolog pairing and formation of chiasmata are both mediated by the DNA repair process called homologous recombination.