1. Meiosis- gamete formation Mader Chapter 17.3

2. Mitosis does not alter the chromosomal makeup of cells

3. Chromosome number must be reduced when gametes are produced

4. Meiosis separates homologous chromosomes

5. There are 2 N Possible arrangements of homologues Humans have 23 pairs of homologous chromosomes N=23 There are 2 23 possible arrangements of homologues = 8,388,608 Four of the eight possible arrangements for a N = 3 organism are shown above. Each Arrangement  2 gametes so there are 8 possible gametes!

6. Crossing over generates even more diversity

7. Meiosis Separates homologous chromosomes Chromosome number goes from 2N  N Generates a very diverse set of gametes each of which contains a nearly unique set of maternal and paternal genes

8. Spermatogenesis

9. Human ova are ovulated arrested in meiotic prophase II

10. The human life cycle