NATS 1675 Lecture Notes - Lecture 7: Sister Chromatids, Synapsis, Meiosis
6 Feb 2018
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223 (for humans) = greater than 8 million. Similar to prophase in mitosis with 2 major exceptions: Synapsis- pairing coming together of homologous chromosomes to form a tetrad. Crossover- equal portions of non-sister chromatids can be exchanged exchange of equal material portions. Purpose of cross over is to further increase genetic variability in gametes. Homologous chromosomes of chromosomes (those that have undergone synapsis) line up at equatorial plate: anaphase i. Pairs of homologous chromosomes will separate: telophase i. Furrow appears, begins to separate cell into 2 cells which will lead to prophase ii. In humans (and other animals) the nuclear envelope will note reform. Nucleus is there around chromosomes: metaphase ii. Chromosomes consisting of 2 sister chromatids line up at equatorial plate: anaphase ii. Sister chromatids separate and move to opposite poles. This anaphase is more like anaphase in mitosis (anaphase 1= separation of homolgous. Chromosomes, anaphase 2= separation of sister chromatids like anaphase in mitosis: telophase ii.
