1. Announcements
Take out Meiosis WS to be checked from last class if you did not get it stamped
Today: Meiosis Review

2. Interphase
Just like in Mitosis:
DNA is replicated

3. Prophase I Just like in mitosis, What’s different:
chromosomes condense and become visible under a microscope (they look like X’s).
nuclear membrane disappears, spindle fibers form
What’s different:
Homologous chromosomes pair up with each other and form a tetrad
Crossing-over (the physical exchange of chromosome parts) occurs. This allows for genetic recombination.

4. Metaphase I
The homologous pairs line up in the middle of the cell (note: this is different than mitosis!)
The chromosomes line up independently of each other

5. Anaphase I
The homologous pairs get pulled by the spindle fibers and are separated to opposite ends of the cell

6. Telophase I
Now a haploid set of chromosomes is at each pole, with each chromosome still having two chromatids.
A nuclear envelope reforms around each chromosome set, the spindle disappears, and cytokinesis (cell pinches off into 2 cells) follows.

7. Prophase II
The 2 haploid cells formed from the end of Telophase I now enter the second phase of meiosis.
The nuclear envelope breaks down, and the spindle apparatus forms.

8. Metaphase II
Single chromosomes line up in the middle of the cell (similar to how chromosomes do in mitosis).

9. Anaphase II
The chromosomes are separated at the centromere, and the two chromatids of each chromosome move to opposite poles on the spindle.

10. Telophase II A nuclear envelope forms around each set of chromosomes.
Cytokinesis takes place, producing four daughter cells (known as gametes), each with a haploid set of chromosomes.

11. MEIOSIS BINGO

12. The exchanging of genetic information between 2 homologous chromosomes.

13. These are the cell parts that pull chromosomes/chromatids to opposite ends of the cell.

14. 2 of these are replicated copies of each other
2 of these are replicated copies of each other. They make up one chromosome (X)

15. Homologous chromosomes are separated at this stage of meiosis

16. This term describes the pinching off of the cell membrane to form 2 new cells at the end of telophase

17. Sperm and egg cells are ___ploid

18. Homologous chromosomes pair up with each other during this phase of meiosis.

19. DNA is replicated during this phase in preparation for cell division.

20. SINGLE chromosomes line up in the middle of the cell during this phase of meiosis.

21. A zygote (a fertilized egg cell) is ___ploid

22. Sister chromatids are separated during this phase of meiosis.

23. At the end of this phase of meiosis, you have haploid cells with INTACT chromosomes.