2. Quick review: identify this stage of the diploid cell cycle.

9. Defined: Process where the chromosome number is reduced by half Gametes created (egg & sperm) End Result: Four Haploid Cells

10. Same process –G1: Growth –S: Chromatin duplicated –G2: Growth

11. Synthesis (S stage) Chromatin strands duplicated

12. Similar as mitosis, except… Two Events: –1) Synapsis: Pairing of homologous chromosomes –Dad’s #1 chromosome pairs with Mom’s #1, etc… –The four paired chromatids equals a TETRAD –2) Crossing Over: Exchange of genes Mom 1 Dad 1

13. Early Prophase daddad mommom mommom daddad daddad mommom Chromosomes form Nucleus dissolves

14. Synapsis daddad mommom mommom daddad daddad mommom Spindle fibers pull homologous chromosomes together tetrad

15. Homologous chromosomes (tetrads) align along cell equator daddad daddad daddad mommom mommom mommom

16. Homologous chromosomes are pulled apart to opposite ends –Tetrads separated mommom daddad mommom daddad daddad mommom

17. Cytokinesis divides the cells Each cell contains 1 of the homologous chromosomes mommom daddad mommom daddad daddad mommom

18. Same as mitosis Note: No new DNA was created (no 2 nd interphase) mommom daddad mommom daddad daddad mommom

19. Remaining chromosomes are aligned at cell equator mommom daddad mommom daddad daddad mommom

20. Sister chromatids are pulled to opposite ends

21. Cytokinesis divides the cells Nucleus reforms on the four new cells Chromatids uncoil End Result: Four haploid cells

22. Defined: Production of sperm cells Location: male testes Makes final changes to sperm cell Four haploid sperm cells at a time Meiosis 1 Meiosis 2 Spermatogenesis spermatogonium

24. Defined: Production of the egg cell (ovum) –In female ovaries During meiosis I: Cytoplasm distributed unequally After meiosis II: –1 cell matures –3 “Polar Bodies” dissolve Meiosis 1 Meiosis 2 Oogenesis oocyte

26. Division of somatic cells Ex: Blood cells, skin cells, nerve cells… End Result: 2 Diploid Cells Importance: Replaces aging cells Importance: Form of asexual reproduction Division of gametes Ex: Sperm and Egg cells End Result: 4 Haploid cells Importance: Reduces the gamete chromosome number by half

27. Kobe Kuiz 1) Name three ways that meiosis and mitosis differ. 2) Pick a stage of meiosis…any stage. Describe what happens in it. 3) What type of cells does meiosis create? 4) What are homologous chromosomes? 5) When do homologous chromosomes move to opposite ends of the cell? 6) When do chromatids move to opposite ends of the cell? 7) Why is no DNA created in meiosis 2? 8) How does meiosis differ in males vs. females?