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Cell division


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Cell division

  1. 1. Cell Division<br />
  2. 2. The Cell Cycle<br />Every hour, about one billion (109) cells die and one billion cells are made in your body<br />
  3. 3. The Cell Cycle<br />Through careful observation, scientists have identified a repeating cycle of events in the life of a cell<br />This cycle of events is called the cell cycle<br />
  4. 4. The Cell Cycle<br />
  5. 5. The Cell Cycle<br />The cell cycle has four phases:<br />G1 Phase – Cell growth<br />S Phase – DNA Replication<br />G2 Phase – Preparation for Mitosis<br />M Phase – Mitosis<br />Interphase<br />
  6. 6. Chromosomes<br />Every cell contains chromosomes<br />Chromosomes are long pieces of coiled DNA and proteins<br />
  7. 7. Chromosomes<br />Chromosomes are only visible when the cell is dividing.<br />When the cell is not dividing, the DNA and proteins are spread throughout the cell as chromatin<br />
  8. 8. Chromosomes<br />At the beginning of cell division, the chromosomes condense into visible structures<br />Dude, mitosis starts in five minutes… I can’t believe you’re not condensed yet!<br />
  9. 9. Chromosomes<br />
  10. 10. Chromosomes<br />Before cell division can occur, each chromosome is copied so that each chromosome consists of two identical sister chromatids<br />When cells divide, one chromatid goes to each of the new cells<br />
  11. 11. The Cell Cycle<br /><ul><li>Recall that a cell spends about 90% of its time in interphase
  12. 12. G1 Phase – Cell growth
  13. 13. S Phase – DNA Replication
  14. 14. G2 Phase – Preparation for Mitosis
  15. 15. M Phase – Mitosis</li></ul>Interphase<br />
  16. 16. Interphase<br />During interphase, the cell takes in nutrients, grows and conducts other normal cell functions<br />
  17. 17. First Growth Phase (G1)<br />The G1 Phase is a period of growth for the cell<br />During this phase, new proteins and organelles are produced<br />
  18. 18. Synthesis Phase (S)<br />During the S Phase, the cell makes (synthesizes) an entire copy of the DNA of the cell<br />
  19. 19. Second Growth Phase (G2)<br />During the G2 Phase, the cell produces the organelles and structures needed for cell division<br />The G2 Phase is the shortest part of interphase<br />
  20. 20. Cell Division<br />Once the cell is ready to divide and make two new identical cells, it enters mitosis (M Phase)<br />During the M Phase, all of the cell’s energy is devoted to the process of cell division<br />
  21. 21. Mitosis<br />There are four phases in mitosis:<br />Prophase<br />Metaphase<br />Anaphase<br />Telophase(and Cytokinesis)<br />
  22. 22. Mitosis<br />At the end of telophase, two daughter cells are formed, each containing identical genetic information<br />
  23. 23. Prophase<br />During prophase, the chromatin (DNA and proteins) that makes up the chromosomes condenses<br />The DNA has already been replicated, so the chromosomes contain two identical sister chromatids<br />
  24. 24. Metaphase<br />During metaphase, the chromosomes line up at the center of the cell<br />Spindle fibers extend from the poles of the cell and attach to the centromeres of each chromosome<br />
  25. 25. Anaphase<br />During anaphase, the sister chromatids separate at the centromere<br />The separated chromosomes are pulled to opposite ends of the cell<br />
  26. 26. Telophase & Cytokinesis<br />During telophase, the cell divides the cytoplasm into two portions<br />The process of splitting the cytoplasm is known as cytokinesis<br />
  27. 27. Telophase & Cytokinesis<br />
  28. 28. Telophase & Cytokinesis<br />
  29. 29. Telophase & Cytokinesis<br />
  30. 30. Interphase<br />
  31. 31. Cell Death<br />The cell cycle regulates how long a cell lives<br />Sometimes cells die because they have suffered injury or damage that cannot be repaired<br />
  32. 32. Apoptosis<br />A cell also dies when it is no longer needed or useful to the organism<br />This regulated or controlled cell death is called apoptosis<br />The cell on the bottom is healthy and normal, while cell on the top is undergoing apoptosis.<br />