1. Meiosis

2. Vocabulary
Homologous Chromosomes – Refers to chromosomes that each have a corresponding chromosome from the opposite-sex parent

3. Diploid vs. Haploid
Diploid - a cell containing both sets of homologous chromosomes
Diploid means “2 sets”
Chromosome number shown as 2N

4. Diploid vs. Haploid
Haploid - a cell with only 1 set of homologous chromosomes
Haploid means “1 set”
Chromosome number shown as N

5. Tetrad
When each pair of homologous chromosomes have replicated/duplicated, they form tetrads
(4 chromatids)

6. Interphase
DNA replication- during “S” phase

7. Meiosis Making of haploid gametes egg, pollen, sperm
In humans = 23 chromosomes

8. Prophase I
1. Prophase I
Homologous chromosomes pair up, forming tetrads
Tetrads

9. Crossing Over Happens during tetrad formation
There is an exchange of genes or alleles
Produces new combinations of alleles

10. Metaphase I 2. Metaphase I
Chromosomes are lined up at the center of the cell
Spindle fibers attach to chromosomes at the centromeres

11. Anaphase I
3. Anaphase I 
Spindle fibers pull homologous chromosomes to opposite ends

12. Telophase I & Cytokinesis
4. Telophase I and Cytokinesis
Nuclear membranes form
Cells separate into two haploid (N) cells
Which picture is cytokinesis?
Which picture is telophase I?

13. Prophase II
Chromosomes form

14. Metaphase II Chromosomes are lined up at the center of the cell
Spindle fibers attach to chromosomes at the centromeres

15. Anaphase II
Sister chromatids separate and move toward opposite ends of cell

16. Telophase II & Cytokinesis
Results in 4 haploid (N) daughter cells

17. The End Result THE RESULTS
Each daughter cell is genetically different from the others
Male haploid gametes = sperm
Female = 1 egg (oocyte) & 3 polar bodies

18. What are the steps of meiosis?
Rewatch
Meiosis
Video