BIOL 1090 Lecture Notes - Lecture 16: Kinetochore, Oogenesis, Sporophyte
5 Apr 2015
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March 05, 2014 n number of chromosomes = the haploid state. Meiosis i: prophase i: leptonema chromosomes, each consisting of two sister chromatids, begin to condense prophase i: zygonema: homologous chromosomes begin to pair. Prophase i: pachnema homologous chromosomes are fully paired prophase i: diplonema homologous chromosomes separate, except at chiasmata. Pairing of homologous chromosomes is called synapsis and is often facilitated by formation of a synaptonemal complex. Prophase i: ppachynema homologous chromosomes are fully paired. Crossing over involves breakage of chromatids and the exchange of broken pieces between homologous chromosomes. (non-sister chromatids) Following crossing over, homologous chromosomes start to pull apart, but remain joined at the cross over junctions (called chiasmata) The cell division in meiosis i is also called a reduction division. prophase i: diakinesis paired chromosomes condense further and become attached to spindle fibres metaphase i paired chromosomes align on the equatorial plane in the cell.
