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Chapter 13 Meiosis and Sexual Life Cycles

Chapter 13 Meiosis and Sexual Life Cycles. 13.2. Asexual reproduction: Single individual is sole parent, passes copies of all its genes to its offspring (exact copies, or clones, of the parent).

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Chapter 13 Meiosis and Sexual Life Cycles

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  1. Chapter 13Meiosis and Sexual Life Cycles

  2. 13.2 Asexual reproduction: Single individual is sole parent, passes copies of all its genes to its offspring (exact copies, or clones,of the parent)

  3. Offspring resembles their parents more than they do less closely related individuals of the same species 13.1 Sexual reproduction: Two parents give rise to offspring that have unique combinations of genes inherited from the two parents (offspring varies genetically from their siblings and their parents).

  4. Genetics: The study of heredity and hereditary variation 13.3. Human karyotype. A display of condensed chromosomes displayed in pairs

  5. 13.4. Chromosomes in a cell with a diploid number of 6 (2n=6) or 3 homologous pair. Each of the 6 chromosomes consist of 2 sister chromatids, joined at the centromere. locus

  6. Fig. 13.5. Human life cycle Fertilization and meiosis must alternate in all sexual life cycles

  7. 13.6. Three types of sexual life cycles. Note alternation of meiosis and fertilization

  8. Concept 13.3:Meiosis reduces the number of chromosome sets from diploid to haploid • Like mitosis, meiosis is preceded by the replication of chromosomes • Meiosis takes place in two sets of cell divisions, called meiosis I and meiosis II • The two cell divisions result in four daughter cells, rather than the two daughter cells in mitosis • Each daughter cell has only half as many chromosomes as the parent cell

  9. 13.7. Overview of meiosis. How meiosis reduces the number of chromosomes. Meiosis takes place in two sets of cell divisions, called meiosis I and meiosis II. The two cell divisions result in four daughter cells, rather than the two daughter cells in mitosis. Each daughter cell has only half as many chromosomes as the parent cell.

  10. 13.8a. The meiotic division of an animal cell. Synapsis Crossing over Interkinesis

  11. 13.8b. The meiotic division of an animal cell.

  12. Differences between mitosis and meiosis II? 13.9. Comparison of meiosis and mitosis.

  13. 13.9. Comparison of meiosis and mitosis.

  14. 13.10. Independent assortment of homologous chromosomes in meiosis.

  15. 13.11. The results of crossing over during meiosis.

  16. 13.12. The results of crossing over during meiosis.

  17. 13.12. The results of crossing over during meiosis.

  18. 13.12. The results of crossing over during meiosis.

  19. 13.12. The results of crossing over during meiosis.

  20. Example question • A cell has a diploid chromosome number of 2n = 4. We will designate these four as chromosomes A, B, C, and D. If meiosis occurred WITH the formation of homologous pairs AC and BD, and the chromosomes were then distributed randomly between the resulting cells, how many gametes could be formed? A) 6 (AB, AC, AD, BC, BD, and CD) B) 3 (AB, BC, and CD) C) 4 (AB, AD, BC, and CD) D) 2 (AB and CD) E) 5 (AB, AC, AD, BC, and CD)

  21. Aneuploidy 15.13. Meiotic non-disjunction

  22. 15.14. Alteration of chromosome structure

  23. Chapter 13 Review (see p.260-261) • 13.1. Offspring acquire genes from parents by inheriting chromosomes. • 13.2. Fertilization and meiosis alternate in sexual life cycles. • 13.3. Meiosis reduces the number of chromosome sets from diploid to haploid. • 13.4. Genetic variation produced in sexual life cycles contributes to evolution.

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