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Chapter Ten Lecture- Mitosis

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Chapter Ten lecture for Lab Bio on mitosis

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Chapter Ten Lecture- Mitosis

  1. 1. Copyright Pearson Prentice Hall Biology
  2. 2. 10–1 Cell Growth Copyright Pearson Prentice Hall
  3. 3. Limits to Cell Growth Larger cells demand more from their DNA and they have trouble moving enough nutrients and wastes across the cell membrane. Copyright Pearson Prentice Hall
  4. 4. The rate of transport in and out of the cell is dependent on the surface area of the cell. The bigger a cell is the more nutrients it will need transported in and the more waste it will need transported out. Copyright Pearson Prentice Hall
  5. 5. A cells volume increases faster than its surface area. This makes it more difficult for large cells to transport materials quickly enough for the cell to survive. Copyright Pearson Prentice Hall
  6. 6. Copyright Pearson Prentice Hall
  7. 7. Before it becomes too large, a growing cell divides forming two “daughter” cells. The process by which a cell divides into two new daughter cells is called cell division. Interphase is the period of growth that occurs between cell divisions. Copyright Pearson Prentice Hall
  8. 8. Copyright Pearson Prentice Hall
  9. 9. 10-2 Cell Division Copyright Pearson Prentice Hall
  10. 10. Eukaryotic cell division occurs in two major stages. First, mitosis divides the cell nucleus. Second, cytokinesis divides the cell’s cytoplasm.
  11. 11. Chromosomes Chromosomes Genetic information is passed from one generation to the next on chromosomes. Before cell division, each chromosome is copied. Copyright Pearson Prentice Hall One copy two copies
  12. 12. Chromosomes Each chromosome consists of two identical “sister” chromatids. Each pair of chromatids is attached at an area called the centromere. Copyright Pearson Prentice Hall Sister chromatids Centromere
  13. 13. Chromosomes When the cell divides, the chromatids separate. Each daughter cell gets one chromatid, so they have the same number of chromosomes as the parent cell. Copyright Pearson Prentice Hall
  14. 14. The cell cycle is the series of events that cells go through as they grow and divide. During the cell cycle: a cell grows prepares for division divides to form two daughter cells, each of which begins the cycle again Copyright Pearson Prentice Hall
  15. 15. The cell cycle has four phases: •G1 (First Gap Phase) •S Phase (DNA Synthesis) •G2 (Second Gap Phase) •M Phase (Mitosis) Copyright Pearson Prentice Hall
  16. 16. During G1, the cell •increases in size •synthesizes new proteins and organelles Copyright Pearson Prentice Hall
  17. 17. Events of the Cell Cycle During the S phase, chromosomes are replicated DNA synthesis takes place Once a cell enters the S phase, it usually completes the rest of the cell cycle. Copyright Pearson Prentice Hall
  18. 18. Events of the Cell Cycle The G2 Phase (Second Gap Phase) organelles and molecules required for cell division are produced Once G2 is complete, the cell is ready to start the M phase—Mitosis G1 + S + G2 = Interphase Copyright Pearson Prentice Hall
  19. 19. Copyright Pearson Prentice Hall Cell Cycle Cell Division Active art
  20. 20. Biologists divide mitosis into four phases: Prophase Metaphase Anaphase Telophase Copyright Pearson Prentice Hall
  21. 21. Mitosis Mitosis Copyright Pearson Prentice Hall Mitosis movie
  22. 22. Spindle forming Copyright Pearson Prentice Hall Prophase Chromosomes (paired chromatids) Centromere Click to Continue
  23. 23. Prophase is the first and longest phase of mitosis. The centrioles separate and take up positions on opposite sides of the nucleus. Chromosomes Copyright Pearson Prentice Hall (paired chromatids) Spindle forming Centromere
  24. 24. The centrioles lie in a region called the centrosome. The centrosome helps to organize the spindle, a fanlike microtubule structure that helps separate the chromosomes. Chromosomes Copyright Pearson Prentice Hall (paired chromatids) Spindle forming Centromere
  25. 25. Chromatin condenses into chromosomes. The centrioles separate and a spindle begins to form. During prophase, the nuclear envelope breaks down. Copyright Pearson Prentice Hall Chromosomes (paired chromatids) Spindle forming Centromere
  26. 26. Copyright Pearson Prentice Hall Centriole Spindle Centriole Click to Continue Metaphase
  27. 27. Metaphase The second phase of mitosis is metaphase. The chromosomes line up across the center of the cell. The centromere connects to the poles of the spindle. Copyright Pearson Prentice Hall Centriole Spindle
  28. 28. Individual chromosomes Copyright Pearson Prentice Hall Anaphase
  29. 29. Individual chromosomes Anaphase Anaphase is the third phase of mitosis. The sister chromatids are pulled apart by the spindle into two separate chromosomes. Copyright Pearson Prentice Hall
  30. 30. Copyright Pearson Prentice Hall Nuclear envelope reforming Telophase
  31. 31. Telophase Telophase is the fourth and final phase of mitosis. Chromosomes gather at opposite ends of the cell and lose their distinct shape. Copyright Pearson Prentice Hall
  32. 32. In telophase, a new nuclear envelope forms around each cluster of chromosomes. Copyright Pearson Prentice Hall
  33. 33. Cytokinesis is not a part of mitosis. Cytokinesis Copyright Pearson Prentice Hall Cytokinesis movie
  34. 34. During cytokinesis, the cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes Copyright Pearson Prentice Hall
  35. 35. In plants, a structure known as the cell plate forms midway between the divided nuclei. Cell plate Cell wall Copyright Pearson Prentice Hall
  36. 36. The cell plate gradually develops into a separating membrane. A cell wall then begins to appear in the cell plate. Copyright Pearson Prentice Hall
  37. 37. 10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall
  38. 38. Copyright Pearson Prentice Hall Controls on Cell Division Controls on Cell Division Experiments show that normal cells will reproduce until they come into contact with other cells. When cells come into contact with other cells, they respond by not growing. This demonstrates that controls on cell growth and division can be turned on and off.
  39. 39. Controls on Cell Division Copyright Pearson Prentice Hall Contact Inhibition
  40. 40. Cell Cycle Regulators The cell cycle is regulated by a specific protein. The amount of this protein in the cell rises and falls in time with the cell cycle. Scientists called this protein cyclin because it seemed to regulate the cell cycle. Cyclins regulate the timing of the cell cycle in eukaryotic cells. Copyright Pearson Prentice Hall
  41. 41. Cyclins were discovered during a similar experiment to this one. A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G2 of interphase. As result, the second cell enters mitosis.
  42. 42. Internal Regulators Proteins that respond to events inside the cell are called internal regulators. Internal regulators allow the cell cycle to proceed only when certain processes have happened inside the cell. Copyright Pearson Prentice Hall
  43. 43. External Regulators Proteins that respond to events outside the cell are called external regulators. External regulators direct cells to speed up or slow down the cell cycle. Copyright Pearson Prentice Hall
  44. 44. Uncontrolled Cell Growth Cancer is a disorder in which some of the body's own cells lose the ability to control growth. Cancer cells do not respond to the signals that regulate the growth of most cells.
  45. 45. Cancer cells divide uncontrollably and form masses of cells called tumors that can damage the surrounding tissues. Cancer cells may break loose from tumors and spread throughout the body, disrupting normal activities and causing serious medical problems or even death. Copyright Pearson Prentice Hall
  46. 46. Practice questions are not part of the lecture notes, so you don’t need to copy them even though they are black. Have a nice day! ☺
  47. 47. Copyright Pearson Prentice Hall 10–1 As a cell increases in size, which of the following increases most rapidly? a. surface area b. volume
  48. 48. Copyright Pearson Prentice Hall 10–1 If an imaginary cube-shaped cell has a length of 6 cm, its ratio of surface area to volume is a. 1 : 1. b. 6 : 1. c. 36 : 1. d. 1 : 6.
  49. 49. Copyright Pearson Prentice Hall 10–1 The process by which a cell divides into two new daughter cells is called a. cell growth. b. cell division. c. DNA replication. d. cell multiplication.
  50. 50. Copyright Pearson Prentice Hall 10–1 When one cell divides in two, what happens to the surface area to volume ratios in the new cells? a. There is no change in the amount of material exchanged. b. Each new cell can exchange more material than the original cell. c. Each new cell can exchange less material than the original cell. d. The two new cells cannot be compared to the original cell.
  51. 51. Copyright Pearson Prentice Hall 10–1 When a growing cell undergoes cell division, each new cell gets a. half the DNA from the original cell. b. twice as much DNA as the original cell. c. a random sample of the DNA in the original cell. d. a full copy of all the DNA in the original cell.
  52. 52. Copyright Pearson Prentice Hall 10-2 The series of events that cells go through as they grow and divide is called a. the cell cycle. b. mitosis. c. interphase. d. cytokinesis.
  53. 53. Copyright Pearson Prentice Hall 10-2 The phase of mitosis during which the chromosomes line up across the center of the cell is a. prophase. b. metaphase. c. anaphase. d. telophase.
  54. 54. Copyright Pearson Prentice Hall 10-2 Cytokinesis usually occurs a. at the same time as telophase. b. after telophase. c. during interphase. d. during anaphase
  55. 55. Copyright Pearson Prentice Hall 10-2 DNA replication takes place during the a. S phase of the cell cycle. b. G1 phase of the cell cycle. c. G2 phase of the cell cycle. d. M phase of the cell cycle.
  56. 56. Copyright Pearson Prentice Hall 10-2 During mitosis, “sister” chromatids separate from one another during a. telophase. b. interphase. c. anaphase. d. metaphase.
  57. 57. Copyright Pearson Prentice Hall 10-3 The cell cycle is believed to be controlled by proteins called a. spindles. b. cyclins. c. regulators. d. centrosomes.
  58. 58. Copyright Pearson Prentice Hall 10-3 Proteins that respond to events inside the cell are called a. internal regulators. b. external regulators. c. cyclins. d. growth factors.
  59. 59. Copyright Pearson Prentice Hall 10-3 Once a multicellular organism reaches adult size, the cells in its body a. stop dividing. b. grow and divide at different rates, depending on the type. c. have the same life span between cell divisions. d. undergo cell division randomly.
  60. 60. Copyright Pearson Prentice Hall 10-3 One effect of an internal regulator is that a cell will not begin mitosis until a. it becomes too large. b. the cell’s growth is stimulated. c. it is in physical contact with other cells. d. all its chromosomes have been replicated.
  61. 61. Copyright Pearson Prentice Hall 10-3 One factor common to almost all cancer cells is a. a lack of cyclin. b. a defect in gene p53. c. exposure to tobacco smoke. d. exposure to radiation.

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