1. Chapter 13 Meiosis and Sexual Life Cycles

2. Question? u Does Like really beget Like? u The offspring will “resemble” the parents, but they may not be “exactly” like them.

3. Heredity

4. Genetics

5. Genes

6. Reproduction

7. Asexual Reproduction

8. Asexual Bud

9. Advantages

10. Disadvantages

11. Sexual Reproduction

12. Advantages

13. Disadvantages

14. Question ? u Do parents give their whole DNA copy to each offspring?

15. Chromosome Number

16. Life Cycle - if Mitosis Female 46 Male 46 egg 46 sperm 46 Zygote 92 mitosis Mitosis

17. Result

18. Life Cycle - if Meiosis Female 46 Male 46 egg 23 sperm 23 Zygote 46 mitosis Meiosis

19. Result

20. Meiosis - Purpose

21. Sexual Life Cycle

23. Ploidy

24. Diploid

27. Haploid

28. Polyploids

29. Life Cycle Variations

30. Meiosis/Mitosis Preview of differences

32. Meiosis

34. LE 13-9 Propase Duplicated chromosome (two sister chromatids) Chromosome replication 2n = 6 Parent cell (before chromosome replication) Chromosome replication MITOSISMEIOSIS Chiasma (site of crossing over) MEIOSIS I Prophase I Tetrad formed by synapsis of homologous chromosomes Tetrads positioned at the metaphase plate Metaphase I Chromosomes positioned at the metaphase plate Metaphase Anaphase Telophase Homologues separate during anaphase I; sister chromatids remain together Sister chromatids separate during anaphase Daughter cells of meiosis I Haploid n = 3 Anaphase I Telophase I MEIOSIS II Daughter cells of mitosis 2n2n 2n2n n Sister chromatids separate during anaphase II n nn Daughter cells of meiosis II

35. Prophase I

37. Metaphase I

38. Anaphase I u.u.

41. Telophase I

42. Interkinesis

43. Meiosis II

44. Meiosis - Results

46. Sexual Sources of Genetic Variation 1.

47. Independent Assortment

49. Gamete Possibilities

50. Random Fertilization

52. Result u Is it any wonder that two offspring from the same human parents only resemble each other and are not identical twins?

53. Crossing-Over

54. Chiasmata

56. Importance

58. Comments

60. Summary u Know how the chromosomes separate during Meiosis. u Know how Meiosis differs from Mitosis. u Know how sexual reproduction increases genetic variation.