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Mitosis and meiosis


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Mitosis and meiosis

  1. 1. Cell Division The Cell Cycle and Meiosis
  2. 2. Somatic Cellular Reproduction: The Cell Cycle and Mitosis
  3. 3. Cells that make up the “body”. Somatic Cells
  4. 4. Why do Somatic Cells Divide Reproduction Growth Repair Development Surface : Volume Maintain chromosome number
  5. 5. Structures that contain the genetic material Chromosomes
  6. 6. Chromosomes Composed of chromatin and proteins
  7. 7. Each Chromosome (after the S phase) contains two identical parts called “sister chromatids” attached at a centromere (referred to as “double stranded”)
  8. 8. • Interphase and Mitosis • The cycle of growth and division in all cells The Cell Cycle
  9. 9. Interphase
  10. 10. Prophase
  11. 11. Metaphase
  12. 12. • Either of two submicroscopic attachment points for chromosomal microtubules, present on each centromere during the process of cell division Kinetochore
  13. 13. Mitotic Spindle made of microtubules
  14. 14. • Several microtubules joined together create structures known as spindle fibers which guide chromosomes during mitosis. Spindle Fibers Spindle Fibers Spindle Fibers
  15. 15. Anaphase
  16. 16. Telophase
  17. 17. Cytokinesis
  18. 18. Identify the Stages of Mitosis 1 2 3 4 5
  19. 19. Cell Cycle Regulation Checkpoints during each phase Signals registered at the checkpoints report the status of various cellular conditions (e.g., Is the environment favorable? Is the cell big enough? Is all DNA replicated?
  20. 20. Molecular protein clocks that regulate the activities of the cell cycle in a particular order Levels controlled by genes: Proto-Onco Genes Stimulate Tumor Supressor Genes Inhibit (p53 is a common example) p53 is a protein that functions to block the cell cycle if the DNA is damaged. If the damage is severe this protein can cause apoptosis (cell death). Cyclin Dependent Kinases
  21. 21. Cell Growth and Division Also Regulated By External Factors: Density Growth Factors
  22. 22. Cancer Cancer cells do not respond normally to the body's control mechanisms. They divide excessively, invade other tissues and, if unchecked, can kill the whole organism. Abnormal cells which have escaped normal cell-cycle controls are the products of mutated or transformed normal cells. A p53 mutation is the most frequent mutation leading to cancer because it prevents apoptosis.
  23. 23. Malignant Tumors and Metastasis
  24. 24. Meiosis
  25. 25. Why Meiosis? Sexual reproduction Reduction of chromosome number Genetic recombination
  26. 26. Prophase I
  27. 27. Metaphase I
  28. 28. Anaphase I
  29. 29. Telophase I
  30. 30. Meiosis I
  31. 31. Prophase II
  32. 32. Metaphase II
  33. 33. Anaphase II
  34. 34. Telophase II
  35. 35. Meiosis II
  36. 36. Crossing-Over
  37. 37. Nondisjunction