1. The Birds and the Bees: Meiosis Chapter 10

2. Meiosis exists for two major reasons: To divide the number of chromosomes To create genetic variability

3. Haploid v. Diploid Cells Haploid- (n) number of chromosomes where (n) is the number of sets of chromosomes. Humans have 23 different types of chromosomes. Diploid- (2n), or a cell that has two sets of chromosomes

4. Soooo….. Sperm and egg are haploid. They each have only 23 chromosomes. 23 Chromosomes

5. Zygote When the (n) sperms enters the (n) egg, we get 2n= 2n number of chromosomes, or in the case of a human, 2(23)= 46 The zygote (a fertilized egg) has 46 chromosomes

6. Steps in Meiosis

7. IN THE FIRST CELLULAR DIVISION, NO CENTROMERES DIVIDE!!! SISTER CHROMATIDS

8. IN MEIOSIS II, ALL WE HAVE ARE TWO CELLS DOING MITOSIS!

9. FROM ONE “GERM CELL” WE PRODUCED 4 GENETICALLY DIVERSE GAMETES !