1. Meiosis
Why We Are Who We Are

2. Warm Up
Why do you think you don’t you look exactly like your biological parents?
Meiosis video

3. Meiosis Takes place in the Gametes (sex cells) of an organism
People have a Chromosome count of 46
When an egg joins a sperm the count must stay at 46 to remain human
So, the egg can only have 23 chromosomes, and the sperm can only have 23 chromosomes
How does this happen?

4. + = Sperm (23) + Egg (23) = Fertilized Cell (46)
During Meiosis gamete (sex) cells undergo a “double division” reducing the chromosomal count to 23. + =
Sperm (23) + Egg (23) = Fertilized Cell (46)

5. Original Gamete Metaphase Anaphase Telophase Cytokinesis
2 Daughter Cells Metaphase 2 Anaphase 2 Telophase 2 Cytokinesis – 4 Gametes

6. List the steps of the cell cycle in the mitosis column
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

7. Mitosis Meiosis Purpose To make BODY cells To grow To repair injuries
To make SEX cells for reproduction Sex cells = gametes = eggs and sperm cells

8. Mitosis Meiosis Which cells do it Happens in all BODY cells
Happens in SEX organs of eukaryotes to make SEX cells

9. Mitosis Meiosis # Daughter Cells TWO daughter cells
FOUR daughter cells

10. Mitosis Meiosis How much DNA
In Eukaryotes, SAME amount of DNA as parent cell. Daughter cells identical to parent cell
In Eukaryotes, HALF as much DNA as parent cell. Daughter cells are ready to combine with another sex cell to reproduce.

11. Mitosis Meiosis In Humans:
TWO sets of 23 chromosome: One set inherited from mom and one set inherited from dad
ONE set of 23 chromosomes: MIXED from parent’s DNA

12. Mitosis Meiosis Remember
My-TOE- sis Mitosis makes body cells for growth and repair
Mini-Meiosis Meiosis makes SEX cells to make a mini me.

13. Interphase
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2
Cytokinesis

14. Meiosis ensures that all living organisms will maintain both Genetic Diversity and Genetic Integrity

15. 4 2 2 46 23 SUPER SLUETH! How many divisions occur in Meiosis?
How many cells result from the end of Meiosis one?
How many cells are produced at the end of Meiosis two?
How do sex cells differ from the parent cell?
Meiosis begins with ______ chromosomes.
Meiosis ends with ____ chromosomes. 4 2 2 46 23
½ the chromosomes

16. These two girls are twins
These two girls are twins. How is it possible that they look so differently?

17. 4. Ending # of Chromosomes
Mitosis
Meiosis
1. What type of cells?
2. Starting # of Cells
3. Ending # of Cells
4. Ending # of Chromosomes

18. Meiosis
Mitosis