1. Meiosis Notes

2. Now…let’s review chromosomes!2

3. Steps of Meiosis: Before Meiosis = INTERPHASE First Part: Meiosis I!
Meiosis is made of two parts: Meiosis I and Meiosis II
First: BEFORE meiosis occurs, there is the “IN BETWEEN PHASE”
Before Meiosis = INTERPHASE
First Part: Meiosis I!
Prophase I (CROSSING OVER OCCURS HERE!)
Metaphase I
Anaphase I (HOMOLOGOUS CHROMOSOMES ARE SEPARATED)
Telophase I
Cytokinesis 3

4. Steps of Meiosis: Second Part: Meiosis II! Prophase II Metaphase II
Anaphase II (SISTER CHROMATIDS ARE SEPARATED)
Telophase II
Cytokinesis 4

5. Prophase 1 Crossing over occurs! Creates new gene combinations!
Chromosomes become visible and the nuclear membrane breaks apart
Crossing over occurs!
Creates new gene combinations!

6. Metaphase 1 vs. 2
Metaphase 1- homologous chromosomes pair up in the middle
Metaphase 2- single chromosomes line up in the middle

7. Anaphase 1 vs. 2
Anaphase 1- homologous chromosomes separate and move apart
Anaphase 2- Chromatids separate and move apart

8. Telophase 1 vs. 2
Telophase 1- Single cell splits into 2 cells, goes right into Prophase 2
Telophase 2- Two cells each split, creating 4 haploid cells

9. Meiosis: A Second Look

10. Meiosis results in 4 genetically different haploid daughter cells
One major point!
Meiosis results in 4 genetically different haploid daughter cells
*These cells are sperm and eggs!

11. 11

12. 12

13. Fertilization + = n 2n n Haploid Egg cell 23 chromosomes Haploid
Sperm cell
23 chromosomes
Diploid
Zygote
46 chromosomes

14. Questions: What are some similarities between MITOSIS and MEIOSIS?
What are some differences between MITOSIS and MEIOSIS?
Why do organisms need to go through mitosis?
Why do organisms need to go through meiosis?
Which organisms undergo mitosis?
Which organisms undergo meiosis?

15. Prove You Know It!
What is the name of the process that creates gametes?
What is the difference between a HAPLOID cell and a DIPLOID cell?
What are the two main parts of meiosis?