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Chapter 8 Bio


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Chapter 8 Bio

  1. 1. CHAPTER 8 <ul><li>Cellular Reproduction: Cells from Cells </li></ul>
  2. 2. Biology and Society: A $50,000 Egg! <ul><ul><li>A few years ago, a sterile couple was willing to pay $50,000 to a woman willing to donate her eggs. </li></ul></ul>Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  3. 3. <ul><ul><li>Infertility </li></ul></ul><ul><ul><ul><li>affects one in ten American couples. </li></ul></ul></ul><ul><ul><li>In vitro fertilization (IVF) can help infertile couples. </li></ul></ul><ul><ul><ul><li>A sperm and an egg are joined in a petri dish. </li></ul></ul></ul><ul><ul><ul><li>The embryo is implanted into the mother’s uterus. </li></ul></ul></ul><ul><ul><ul><li>IVF is one of many reproductive technologies. </li></ul></ul></ul>
  4. 4. Figure 8.1
  5. 5. What Cell Reproduction Accomplishes <ul><ul><li>Reproduction </li></ul></ul><ul><ul><ul><li>Is the birth of new organisms. </li></ul></ul></ul><ul><ul><ul><li>Occurs much more often at the cellular level. </li></ul></ul></ul>Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  6. 6. <ul><li>Cell division plays a role in </li></ul><ul><ul><ul><li>the replacement of lost or damaged cells. </li></ul></ul></ul><ul><ul><ul><li>cell reproduction and growth . </li></ul></ul></ul>
  7. 7. Passing On Genes from Cell to Cell <ul><ul><li>Before a parent cell divides, it duplicates its chromosomes . </li></ul></ul><ul><ul><li>The two resulting “ daughter ” cells are genetically identical. </li></ul></ul>
  8. 8. The Reproduction of Organisms <ul><ul><li>In asexual reproduction , single-celled organisms reproduce by simple cell division . </li></ul></ul>Hydra Budding
  9. 9. Figure 8.2a
  10. 10. <ul><ul><ul><li>Some multi cellular organisms can divide into pieces that then grow into new individuals. </li></ul></ul></ul>
  11. 11. Figure 8.2b
  12. 12. Figure 8.2c
  13. 13. <ul><ul><li>Sexual reproduction is different. </li></ul></ul><ul><ul><ul><li>It requires fertilization of an egg by a sperm. </li></ul></ul></ul><ul><ul><ul><li>Production of egg and sperm is called meiosis . </li></ul></ul></ul>
  14. 14. <ul><ul><li>Almost all of the genes of a eukaryotic cell </li></ul></ul><ul><ul><ul><li>are located on chromosomes in the cell nucleus . </li></ul></ul></ul>The Cell Cycle and Mitosis
  15. 15. Eukaryotic Chromosomes <ul><ul><li>Each eukaryotic chromosome contains one very long DNA molecule , </li></ul></ul><ul><ul><ul><li>typically bearing thousands of genes . </li></ul></ul></ul><ul><ul><li>The number of chromosomes in a eukaryotic cell </li></ul></ul><ul><ul><ul><li>depends on the species . </li></ul></ul></ul>
  16. 16. Figure 8.3
  17. 17. <ul><ul><li>Chromosomes </li></ul></ul><ul><ul><ul><li>made of chromatin , a combination of DNA and protein molecules. </li></ul></ul></ul><ul><ul><ul><li>not visible in a cell until cell division occurs. </li></ul></ul></ul>
  18. 18. Figure 8.4
  19. 19. <ul><ul><li>The DNA in a cell is packed into an elaborate, multilevel system of coiling and folding . </li></ul></ul>DNA Packing
  20. 20. Figure 8.5
  21. 21. <ul><ul><li>Before a cell divides, it duplicates all of its chromosomes, resulting in two copies called sister chromatids . </li></ul></ul>
  22. 22. <ul><ul><li>When the cell divides, the sister chromatids separate from each other. </li></ul></ul>
  23. 23. <ul><li>Prometaphase </li></ul>Mitosis Overview Late Interphase Prophase Metaphase Anaphase Telophase
  24. 24. Figure 8.6
  25. 25. The Cell Cycle <ul><ul><li>Eukaryotic cells that divide undergo an orderly sequence of events called the cell cycle . </li></ul></ul><ul><ul><li>The cell cycle consists of two distinct phases : </li></ul></ul><ul><ul><ul><li>Interphase </li></ul></ul></ul><ul><ul><ul><li>Mitotic phase </li></ul></ul></ul>
  26. 26. Figure 8.7
  27. 27. Mitosis and Cytokinesis <ul><ul><li>Mitosis </li></ul></ul><ul><ul><ul><li>Is the division of the </li></ul></ul></ul><ul><ul><ul><li>chromosomes . </li></ul></ul></ul><ul><ul><ul><li>Is preceded by </li></ul></ul></ul><ul><ul><ul><li>interphase . </li></ul></ul></ul>Mitosis (All Phases) Animal Mitosis
  28. 28. Figure 8.8.1
  29. 29. <ul><ul><li>Mitosis consists of four distinct phases : </li></ul></ul><ul><ul><ul><li>Prophase </li></ul></ul></ul><ul><ul><ul><li>Metaphase </li></ul></ul></ul>
  30. 30. Figure 8.8.2
  31. 31. <ul><ul><ul><li>Anaphase </li></ul></ul></ul><ul><ul><ul><li>Telophase </li></ul></ul></ul>
  32. 32. Figure 8.8.3
  33. 33. <ul><ul><li>Cytokinesis </li></ul></ul><ul><ul><ul><li>Typically occurs during telophase . </li></ul></ul></ul><ul><ul><ul><li>Is the division of the cytoplasm . </li></ul></ul></ul><ul><ul><ul><li>Is different in plant and animal cells. </li></ul></ul></ul>Cytokinesis
  34. 34. Figure 8.9a
  35. 35. Figure 8.9b
  36. 36. Cancer Cells: Growing Out of Control <ul><ul><li>Normal plant and animal cells have a cell cycle control system. </li></ul></ul>
  37. 37. What Is Cancer? <ul><ul><li>Cancer is a disease of the cell cycle . </li></ul></ul><ul><ul><li>Cancer cells do not respond normally to the cell cycle control system. </li></ul></ul>
  38. 38. <ul><ul><li>Cancer cells can form tumors , </li></ul></ul><ul><ul><ul><li>Abnormally growing masses of body cells. </li></ul></ul></ul><ul><ul><li>If a tumor is malignant , </li></ul></ul><ul><ul><ul><li>It can spread to other parts of the body. </li></ul></ul></ul>
  39. 39. Figure 8.10
  40. 40. Cancer Treatment <ul><ul><li>Cancer treatment can involve </li></ul></ul><ul><ul><ul><li>Radiation therapy , which damages DNA and disrupts cell division. </li></ul></ul></ul><ul><ul><ul><li>Chemotherapy , which uses drugs that disrupt cell division. </li></ul></ul></ul>
  41. 41. <ul><ul><li>Cancer cells are often grown in culture for study. </li></ul></ul>
  42. 42. Cancer Prevention and Survival <ul><ul><li>Cancer prevention includes changes in lifestyle: </li></ul></ul><ul><ul><ul><li>NOT smoking </li></ul></ul></ul><ul><ul><ul><li>Exercising adequately </li></ul></ul></ul><ul><ul><ul><li>Avoiding exposure to the sun </li></ul></ul></ul><ul><ul><ul><li>Eating a high-fiber , low-fat diet </li></ul></ul></ul><ul><ul><ul><li>Visiting the doctor regularly </li></ul></ul></ul><ul><ul><ul><li>Performing regular self-examinations </li></ul></ul></ul>
  43. 43. <ul><ul><li>Sexual reproduction depends on </li></ul></ul><ul><ul><ul><li>Meiosis . </li></ul></ul></ul><ul><ul><ul><li>Fertilization . </li></ul></ul></ul>Meiosis:The Basis of Sexual Reproduction Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  44. 44. Figure 8.12
  45. 45. Homologous Chromosomes <ul><ul><li>Different organisms of the same species have the same number and types of chromosomes . </li></ul></ul>
  46. 46. <ul><ul><li>A somatic cell </li></ul></ul><ul><ul><ul><li>Is a typical human body cell. </li></ul></ul></ul><ul><ul><ul><li>Has 46 chromosomes. </li></ul></ul></ul>
  47. 47. <ul><ul><li>A karyotype is an orderly arrangement of chromosomes. </li></ul></ul><ul><ul><li>Homologous chromosomes are matching pairs of chromosomes. </li></ul></ul>
  48. 48. Figure 8.13
  49. 49. <ul><ul><li>Humans have </li></ul></ul><ul><ul><ul><li>Two different sex chromosomes, X and Y . </li></ul></ul></ul><ul><ul><ul><li>Twenty-two pairs of matching chromosomes, called autosomes . </li></ul></ul></ul>
  50. 50. Gametes and the Life Cycle of a Sexual Organism <ul><ul><li>The life cycle of a multicellular organism is the sequence of stages leading from the adults of one generation to the adults of the next. </li></ul></ul>
  51. 51. Figure 8.14
  52. 52. <ul><ul><li>Humans are diploid organisms. </li></ul></ul><ul><ul><ul><li>Their cells contain two sets of chromosomes. </li></ul></ul></ul><ul><ul><ul><li>Their gametes are haploid , having only one set of chromosomes. </li></ul></ul></ul>
  53. 53. <ul><ul><li>Fertilization </li></ul></ul><ul><ul><ul><li>Is the fusion of sperm and egg. </li></ul></ul></ul><ul><ul><ul><li>Creates a zygote, or fertilized egg. </li></ul></ul></ul><ul><ul><li>Sexual life cycles involve an alternation of diploid and haploid stages. </li></ul></ul>
  54. 54. Figure 8.15
  55. 55. The Process of Meiosis <ul><ul><li>In meiosis, </li></ul></ul><ul><ul><ul><li>Haploid daughter cells are produced in diploid organisms. </li></ul></ul></ul><ul><ul><ul><li>Two consecutive divisions occur, meiosis I and meiosis II, preceded by interphase. </li></ul></ul></ul><ul><ul><ul><li>Crossing over occurs. </li></ul></ul></ul>
  56. 56. Figure 8.16.1
  57. 57. Figure 8.16.2
  58. 58. Figure 8.16.3
  59. 59. Review: Comparing Mitosis and Meiosis <ul><ul><li>All the events unique to meiosis occur during meiosis I. </li></ul></ul>
  60. 60. Figure 8.17
  61. 61. The Origins of Genetic Variation <ul><ul><li>Offspring of sexual reproduction are genetically different from their parents and from one another. </li></ul></ul>
  62. 62. <ul><li>Genetic Variation </li></ul>
  63. 63. Random Fertilization <ul><ul><li>The human egg cell is fertilized randomly by one sperm, leading to genetic variety in the zygote. </li></ul></ul>
  64. 64. Crossing Over <ul><ul><li>In crossing over, </li></ul></ul><ul><ul><ul><li>Homologous chromosomes exchange genetic information. </li></ul></ul></ul><ul><ul><ul><li>Genetic recombination occurs. </li></ul></ul></ul>Crossing Over
  65. 65. Figure 8.19
  66. 66. <ul><ul><li>What happens when errors occur in meiosis? </li></ul></ul>When Meiosis Goes Awry
  67. 67. How Accidents During Meiosis Can Alter Chromosome Number <ul><ul><li>In nondisjunction , </li></ul></ul><ul><ul><ul><li>The members of a chromosome pair fail to separate during anaphase. </li></ul></ul></ul><ul><ul><ul><li>Gametes with an incorrect number of chromosomes are produced. </li></ul></ul></ul>Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  68. 68. Figure 8.20
  69. 69. <ul><ul><li>The result of nondisjunction </li></ul></ul>
  70. 70. Figure 8.21
  71. 71. Down Syndrome : An Extra Chromosome 21 <ul><ul><li>Down Syndrome </li></ul></ul><ul><ul><ul><li>Is a condition where an individual has an extra chromosome 21 . </li></ul></ul></ul><ul><ul><ul><li>Is also called trisomy 21 . </li></ul></ul></ul>
  72. 72. Figure 8.22
  73. 73. <ul><ul><li>The incidence of Down Syndrome increases with the age of the mother. </li></ul></ul>
  74. 74. Figure 8.23
  75. 75. Evolution Connection: New Species from Errors in Cell Division <ul><ul><li>Errors in meiosis may have been instrumental in the evolution of many species. </li></ul></ul>Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  76. 76. <ul><ul><li>Polyploids </li></ul></ul><ul><ul><ul><li>Are new species. </li></ul></ul></ul><ul><ul><ul><li>Have more than two sets of homologous chromosomes in each somatic cell. </li></ul></ul></ul>
  77. 77. Figure 8.24