BIOL 1090 Lecture 3: 3.Meiosis and Gametogenesis
Document Summary
The process by which the number of chromosomes in the reproductive cell is reduced from the diploid number (2n ) to half. Like mitosis, meiosis begins with a duplicated genome in which each chromosome has been replicated. End up with 2 diploid, genetically identical cells (2n, 2c) End up with 4 haploid, genetically distinct cells (n,c) Crossing over involves breakage of chromatids and the exchange of the broken pieces between homologous chromosomes. After crossing over, the homologous chromosomes start to pull apart. Chromosome non-disjunction: failure of two homologous chromosomes to separate. Reductional division: the cell division in meiosis i. Chiasmata: points where homologous chromosomes are crossing over chromosomes are crossing over. Resembles a mitotic division, but the products are haploid. One division event follows one round of chromosome duplication. Two cells produced that are identical to each other and to the mother cell from which they were derived.