1. Meiosis

2. Meiosis
Two rounds of cell division (Meiosis I and Meiosis II)
Results in 4 haploid cells
We need this to create gametes (sex cells)

3. Key Terms Homologous chromosomes Sister chromatids
Two separate chromosomes that have the same genes
One from your mother and one from your father
Sister chromatids
Each half of one chromosome
Homologous chromosomes are divided in meiosis I and sister chromatids will be divided in meiosis II.

4. Meiosis Similar process to mitosis Meiosis I Meiosis II Prophase I
Metaphase I
Anaphase I
Telophase I
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II

5. Prophase I
Nuclear membrane breaks down, centrioles move to opposite sides of the cell.
Homologous chromosomes pair up.

6. Prophase I Crossing over
When homologous chromosomes pair, parts of them may break off and reattach to the other.
This increases genetic variation!

7. Metaphase I
Homologous chromosomes line up along the middle of the cell.
Each side has chromosomes from both parents.

8. Anaphase I
Homologous chromosomes separate and move to opposite ends of the cell.

9. Telophase I
Two nuclei are formed
Cytokinesis

10. Meiosis II During Meiosis I, we divided homologous chromosomes.
In Meiosis II, we will divide sister chromatids.

11. Prophase II Nuclear membrane breaks down
Centrioles move to opposite sides of the cell
Same as prophase I or prophase in mitosis!

12. Metaphase II
Chromosomes line up along the middle of the cell.

13. Anaphase II
Sister chromatids pulled apart to opposite sides of the cell.

14. Telophase II Nuclear membrane reforms Cytokinesis
Results in four haploid cells with a combination of genes from both mother and father

16. Gamete Formation
Spermatogenesis= production of four haploid sperm cells from one diploid spermatagonium

17. Gamete Formation
Oogenesis= one diploid oocyte divides unevenly, forming one haploid egg and three unusable polar bodies.

18. Mitosis vs. Meiosis
Cell division

19. Mitosis/Meiosis Review
What kind of cells are produced by mitosis?
What kind of cells are produced by meiosis?
What is the difference between meiosis I and meiosis II?
What is crossing over and when does it occur?
Which process contributes more to genetic diversity (mitosis or meiosis)? Why?

20. Meiosis Simulation
Arrange your “chromosomes” to simulate each stage of meiosis. Draw the chromosome arrangement in the template provided.
Next to each picture, provide a brief description of what occurs during that stage.
When you are finished, answer the following questions:
What is the difference between meiosis I and II?
Which round of meiosis is more similar to mitosis? Why?