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Meiosis and Sexual Life Cycles: Understanding Genetic Variation

This chapter explores the process of meiosis and sexual reproduction, highlighting the advantages and disadvantages of this life cycle. It investigates the sources of genetic variation and the differences between meiosis and mitosis.

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Meiosis and Sexual Life Cycles: Understanding Genetic Variation

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  1. Chapter 13 Meiosis and Sexual Life Cycles

  2. Question? • Does Like really beget Like? • 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 ? • 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 Mitosis

  17. Result

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

  19. Result

  20. Meiosis - Purpose

  21. Sexual Life Cycle

  22. Ploidy

  23. Diploid

  24. Haploid

  25. Polyploids

  26. Life Cycle Variations

  27. Meiosis/Mitosis Preview of differences

  28. Meiosis/Mitosis Preview of differences

  29. Meiosis

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

  31. Prophase I

  32. Prophase I

  33. Metaphase I

  34. Anaphase I • .

  35. Anaphase I

  36. Telophase I

  37. Interkinesis

  38. Meiosis II

  39. Meiosis - Results

  40. Sexual Sources of Genetic Variation 1.

  41. Independent Assortment

  42. Gamete Possibilities

  43. Random Fertilization

  44. Random Fertilization

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