LIFE 102 Lecture Notes - Lecture 32: Sister Chromatids, Synapsis, Metaphase
Document Summary
Three events are unique to meiosis and all occur in meiosis i: synapsis and crossing over in prophase i. Homologous chromosomes physically connect and exchange genetic information: at the metaphase plate, there are paired homologous chromosomes (tetrads), instead of individual replicated chromosomes, at anaphase i, it is homologous chromosomes, instead of sister chromatids, that separate. *sister chromatid cohesion allows sister chromatids of a single chromosome to stay together through meiosis i. Protein complexes that are responsible for this cohesion. Cleaved at the end of metaphase in mitosis. Cleaved in anaphase i and ii in meiosis. During meiosis and fertilization is responsible for most of the variation between generations. Three mechanisms contribute to genetic variation: independent assortment of chromosomes, crossing over, random fertilization. Each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of the other pairs. Homologous portions of two non-sister chromatids trade places.
