1. Learning Targets “I Can…” Contrast mitosis and meiosis. Identify the process that creates gametes (sex cells).

2. MITOSISMEIOSIS

4. Learning Targets “I Can...” -Define “gamete.” -Distinguish between haploid (N) and diploid (2N) cells. -Calculate the haploid (N) number of chromosomes given the diploid (2N) number, and vice versa. -Explain why gametes are haploid. -Describe the major events of meiosis. -Define a “tetrad.”

5. Meiosis The Creation of Gametes

6. Definition Cell division to form gametes (sex cells), which have half the chromosome number of the original cell

7. Stages of Meiosis 1. Interphase: DNA replicates (just like mitosis)

8. Stages of Meiosis 2. Prophase I a. Nucleus disappears b. Replicated DNA condenses into chromosomes c. Homologous chromosomes pair to form tetrads

9. Stages of Meiosis 3. Metaphase I

10. Stages of Meiosis 4. Continues through Anaphase I and Telophase I. By Prophase II...

11. Stages of Meiosis 5. Metaphase II

12. Stages of Meiosis 6. Continues though Anaphase II and Telophase II

14. Stages of Meiosis 7. The four final cells are gametes, either sperm cells or egg cells 8. The gametes are different from the original cell because they only have half the number of chromosomes

15. Why are 4 daughter cells different from the original parent cell?

16. 1. Gametes are haploid. a. One copy of each chromosome b. Haploid cells are designated as N. 2.All other cells are diploid. a. Two copies of each chromosome. b. Diploid cells are designated as 2N.

17. Why are 4 daughter cells different from the original parent cell? 3. Offspring have homologous chromosomes (one set from mom and one set from dad) 4. Each homologous pair has two alleles a. Alleles: alternative forms of genes -Dominant (A) -Recessive (a) b. These alleles get shuffled around between homologous chromosomes during prophase 1 when they are paired in tetrads

18. References http://www.exoticreps.co.uk/mitosis- meiosis.jpghttp://www.exoticreps.co.uk/mitosis- meiosis.jpg http://labspace.open.ac.uk/file.php/2668/S K195_1_008i.jpghttp://labspace.open.ac.uk/file.php/2668/S K195_1_008i.jpg http://homepage1.nifty.com/scilla/sonota/it you/meiosis.jpghttp://homepage1.nifty.com/scilla/sonota/it you/meiosis.jpg http://study.com/academy/lesson/alternatio n-of-generations-the-gametophyte-and- sporophyte.htmlhttp://study.com/academy/lesson/alternatio n-of-generations-the-gametophyte-and- sporophyte.html