1. Meiosis
Ch. 6.2

2. Diploid (2n): two identical copies of every chromosome
Diploid (2n): two identical copies of every chromosome. (ALL somatic cells)
Human diploid # = 46
Haploid (n): one copy of every chromosome. (ONLY sex cells)
Human haploid # = 23
Diploid
Haploid

3. Tetrad Mom Dad Prophase 1 – Meiosis 1 synapsis Synapsis happens.
Crossing-over happens.
Crossing-over results in genetic recombination, which creates more diversity among offspring.
synapsis
Mom
Dad

4. Homologous pair undergoing crossing over
Synapsis: Homologous chromosomes pair up with each other & form a tetrad.
Crossing over: parts of homologous pairs break off and re-form on the adjacent chromosome. Leads to variation!
Homologous pair undergoing crossing over
* Notice: chromosomes are aligned so the genes on one match corresponding genes on the other.

6. Metaphase 1 – homologous pairs line up in the middle of the cell
Spindle fibers attach to one of each chromosome pairs.

7. Anaphase 1 – homologous pairs split apart from each other
Independent assortment happens

9. Independent assortment: Chromosomes separate from each other randomly.

10. Telophase 1 – We end up with 2 haploid cells
Telophase 1 – We end up with 2 haploid cells. These cells enter Meiosis 2

11. Prophase I

12. Metaphase I

13. Anaphase I

14. Telophase I

15. Prophase II

16. Metaphase II

17. Anaphase II

18. Telophase II