1. Mitosis vs. Meiosis
Objective 1

2. Chromosomes X shaped Contain our DNA Humans have 46 (23 pairs)
Each normal cell needs all 46
Gametes (sex cells) need 23

3. Review What are the shape of chromosomes?
How many chromosomes do humans have?
How many chromosomes are in our sex cells?

4. Mitosis Mitosis is regular cell division 1 cell  2 identical cells
99% of all cells are normal cells
46 chromosomes (23 pairs)
1 cell  2 identical cells
Mitosis has 4 phases (steps)
Prophase
Metaphase
Anaphase
Telophase

6. Review What types of cells use mitosis to divide?
What are the phases of mitosis?
How many chromosomes do each daughter cell have after mitosis (in humans)?

7. Meiosis Meiosis is sex cell (gamete) division
23 chromosomes only (no pairs)
1 cell  4 unique gametes (sperm/egg)
Meiosis has 8 steps (phases)
Prophase I 5. Prophase II
Metaphase I 6. Metaphase II
Anaphase I 7. Anaphase II
Telophase I 8. Telophase II

8. Meiosis Part 1 Interphase I Prophase I Metaphase I Anaphase I
Cells undergo a round of DNA replication, forming duplicate Chromosomes.
Each chromosome pairs with its corresponding homologous chromosome to form a tetrad.
Spindle fibers attach to the chromosomes.
The fibers pull the homologous chromosomes toward the opposite ends of the cell.

9. Meiosis Part II Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

10. Visual Web Based Model

11. Review How many cells are made from meiosis?
How many chromosomes do they have (in humans)?
How many phases are in meiosis?

12. Diploid vs. Haploid Diploid cells: Haploid cells: Diploid uses mitosis
Standard cells (99% of all cells)
2 sets of chromosomes (2N)
How do diploid cells divide?
Haploid cells:
Gametes (sex cells)
1 set of chromosomes (1N or N)
How do haploid cells divide?
Diploid uses mitosis
Haploid uses meiosis

13. Answer the following questions in your notes:
How many phases are in mitosis? List them in order.
How many phases are in meiosis? List them in order.
What type of cells do mitosis?
What type of cells do meiosis?
Mitosis makes ___ _________ cells.
Meiosis makes ___ _________ gametes.
Mitosis makes (haploid/diploid) cells, while meiosis makes (haploid/diploid) cells.