What Is the Significance of Meiosis?
(Section 10.3) A. Problem of chromosome duplication is solved. B. Diversity is created 1. Independent assortment of chromosomes makes sure that no two gametes are ever identical, Figure 10.2c, number of possible combinations = 2n 2. Recombination C. Role of meiosis and sex outcome 1. Humans have 22 pairs of autosomes and one pair of sex chromosomes; females have 2 X chromosomes, but males have one X and one Y. 2. Sex chromosomes pair like homologues and separate in meiosis I, so each haploid cell that results has either an X or a Y in males: Figure 10.4 3. Sex is determined by the sperm. 4. Sidebar: The revealing Y chromosome. Every male inherits a Y chromosome from his father that is unchanged because recombination occurs so infrequently with the X. It can be used as a hereditary marker, as in the case of Thomas Jeffersons descendants through Sally Hemings. IV. Gamete Formation in Humans (Section 10.4) A. Spermatogenesis: Figure 10.5a 1. Spermatogoniadiploid cells that can divide by m
