1. Why do some scientist feel that diarrhea is hereditary? It runs in our “genes”/jeans

2. Cell Cycle including Meiosis (known as Gametogenesis)

3. Purpose : To create germ cells, gametes or sex cells. - cells with ½ the number of chromosomes - known as 1N cells -two types of germ cells -sperm -egg / ova -in humans 1N/monoploid # =23 -contains 1 chromosome from each of the 23 pairs.

4. Two types of gametes Spermatogenesis: -meiosis that takes place in the testicles -produces sperm -made starting at puberty and ends at death -occurs everyday at a rate of 120 to 200 million/day Male ReproductioMale Reproduction

5. Oogenesis: -meiosis that takes place in the ovaries -produces ova/eggs -occurs: -during 2 nd month of fetal development -ova stored and released once a month during menstrual cycle -starting at puberty and ending with menopause -each ovary contain approximately 300,000 eggs. Female Reproductive

6. Gametogenesis 1 parent cell divides twice creating four cells with ½ the number of chromosomes. Parent cell is either a testicle or an ovary cells each starting with 46 chromosomes. Meiosis I Meiosis II

7. Interphase I Occurs in testicle or ovary cell, 2N cells DNA replicates

8. Prophase I 1.Chromatin supercoils into chromatid 2.Centrioles split and form spindle fibers 3.Nucleus and nucleolus disassemble 4.Homologous pairs of chromosomes pair up

9. Homologous Chromosomes Chromosomes that carry the same set of genes. One is from your mom and one from your dad.

11. Metaphase I 1.Homologous pairs of chromosomes move to the middle of the cells, each pair lines up on one spindle fiber. 2.Chromosomes line up randomly

12. Anaphase I 1.Homologous pairs of chromosomes split apart and move away to opposite sides of the cell. 2.Asters push against cell membrane causing the cell to elongate.

13. Telophase I with cytokinesis 1.Nucleus and nucleolus reform 2.Cell divides into two/cytokinesis 3.End result is now 2 cells each with 23 replicated chromosomes each.

14. Interphase II DNA does not replicate The rest of meiosis II is identical to mitosis.

17. End result is four cells each with ½ the number of chromosomes.

18. Hyperlink