1. Meiosis

2. Quick review: identify this stage of the diploid cell cycle.
Prophase

3. Quick review: identify this stage of the diploid cell cycle.
telophase

4. Quick review: identify this stage of the diploid cell cycle.
anaphase

5. Quick review: identify this stage of the diploid cell cycle.
metaphase

6. Quick review: identify this stage of the diploid cell cycle.
interphase

7. Meiosis Meiosis
Defined: Process where the chromosome number is reduced by half
Gametes created (egg & sperm)
End Result: Four Haploid Cells

8. Interphase
Same process (G1, S, G2)
Chromatin duplicated

9. Synthesis (S stage)

10. Prophase 1 Similar as mitosis, except… Two Events:
1) Synapsis: Pairing of homologous chromosomes
The four chromatids equal a TETRAD
2) Crossing Over: Exchange of genes

11. Early Prophase

12. Synapsis: Homologous chromosomes align

13. Homologous chromosomes (tetrads) align along cell equator
Metaphase 1
Homologous chromosomes (tetrads) align along cell equator

14. Homologous chromosomes are pulled apart to opposite ends
Anaphase 1
Homologous chromosomes are pulled apart to opposite ends
Tetrads separated

15. Cytokinesis divides the cells
Telophase 1
Cytokinesis divides the cells
Each cell contains 1 of the homologous chromosomes

16. Note: No new DNA was created (no 2nd interphase)
Prophase 2
Same as mitosis
Note: No new DNA was created (no 2nd interphase)

17. Remaining chromosomes are aligned at cell equator
Metaphase 2
Remaining chromosomes are aligned at cell equator

18. Sister chromatids are pulled to opposite ends
Anaphase 2
Sister chromatids are pulled to opposite ends

19. Telophase 2
Nucleus reforms on the four new cells
Cytokinesis divides the cells
Chromatids uncoil
End Result: Four haploid cells

20. Defined: Production of sperm cells Occurs in male testes
Spermato-
genesis
Defined: Production of sperm cells
Occurs in male testes
Meiosis produces four haploid sperm cells at a time

21. Oogenesis Defined: Production of the egg cell (ovum)
During meiosis I: Cytoplasm distributed unequally
After meiosis II:
1 cell matures
3 “Polar Bodies” dissolve
Oogenesis

22. Mitosis Meiosis Division resulting in gametes
Ex: Sperm and Egg cells
End Result: 4 Haploid cells
Importance: Reduces the gamete chromosome number by half
Division of somatic cells
Ex: Blood cells, skin cells, nerve cells…
End Result: 2 Diploid Cells
Importance: Replaces aging cells
Importance: Form of asexual reproduction