1. Meiosis

2. Mitosis Meiosis Copy of a cell VS.
Division in which 4 new cells are made with half of the original DNA
New cells are different than the original cell
Make gametes: sperm and egg
Copy of a cell 46
diploid 46
diploid 46 46 23 23
haploid
diploid
diploid 23 23 23 23
haploid

3. Meiosis Animation

5. I. Meiosis A. Which cells undergo meiosis?
1. Only cells within the testis and the ovaries produce gametes
a. Gametes: haploid sperm and egg
B. Why meiosis?
1. You only want half (23) the number of chromosomes in each sex cell
2. So…you need to have 2 divisions

7. Interphase
Cell grows
DNA replicates

8. Prophase I Tetrads form: homologous pairs buddy up
Crossing Over: parts of the homologous chromosomes switch places
* New combination of traits!

9. Crossing over

10. Metaphase I Homologous chromosomes line up RANDOMLY
Independent assortment
New combinations of traits
*Different than mitosis!

11. Independent Assortment

12. Anaphase I Homologous chromosomes are separated
Sister chromatids stay attached
*Different than mitosis

13. Telophase I and Cytokinesis I
End up with 2 HAPLOID cells
Each cell has one homologous chromosome form the pair 1n 1n

14. Prophase II

15. Metaphase II
Chromosomes line up along equator
*Same as in mitosis

16. Anaphase II
Chromatids are pulled apart
*Like in mitosis

17. Telophase II and Cytokinesis II

19. Gametes produced:
* 4 sperm
* 1 egg and 3 polar bodies
Gametes