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Cell Division

Cell Division. “All cells come from pre-existing cells.” HOW?. PREVIEW VIDEO. Mitosis. MITOSIS. Mitosis – division of somatic cells . In higher organisms, mitosis only occurs in somatic cells such as liver , kidney , and skin .

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Cell Division

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  1. Cell Division “All cells come from pre-existing cells.” HOW? PREVIEW VIDEO

  2. Mitosis MITOSIS • Mitosis – division of somatic cells. • In higher organisms, mitosis only occurs in somatic cells such as liver, kidney, and skin. • Mitosis does not occur in sex cells (spermand egg). X

  3. WHY MITOSIS? • Grow. • Repair and replace.

  4. WHAT ARE CHROMOSOMES? • Chromosomes come in linked pairs called chromatids. • These are held together at a centromere. CHROMATIDS CENTROMERE

  5. What does mitosis look like? • Video of mitosis • Understanding mitosis requires an understanding of the stages of mitosis.

  6. What are the stages of mitosis? • INTERPHASE A. Normal cell function. B. DNA is copied. Plant and animal cells in interphase.

  7. Chromatid Chromatid Centromere DNA Synthesis { { Chromosome after DNA Synthesis Chromosome before DNA Synthesis Interphase

  8. Easier to move when cells divide! PROPHASE • Nuclear membrane dissolves. • Chromosomes condense. CHROMATIN condenses into CHROMOSOMES

  9. Prophase C. SPINDLE FIBERS attach to the CENTROMEREof each chromosome.

  10. Prophase Plant and animal cells in prophase.

  11. Metaphase • Chromosomes line up in middle of the cell. Plant and animal cells in metaphase.

  12. Anaphase • Spindle fibers pull chromatids apart. • Chromatids move to opposite ends. Plant and animal cells in Anaphase.

  13. Telophase and Cytokinesis • Chromosomes reach opposite ends. • Nuclear membrane is remade. • Cytokinesis – cell membrane pinches in to form two new cells. In plants, cell wall forms between both cells.

  14. Telephase and Cytokinesis Plant and animal cells in Telophase.

  15. Cytokinesis

  16. A good way of remembering the stages of mitosis is: I Prefer Mangoes After Tea

  17. Mitosis OVERALL GOAL OF MITOSIS • Divide one cell into two cells. • Keep the chromosome number the same.

  18. ANIMATION OF PLANT CELL MITOSIS – click on “Plant Cell Mitosis” on left MITOSIS IN NEWT LUNG CELLS – click on “Live Animal Mitosis” on left MITOSIS VIDEO QUIZ

  19. PLANT CELL INTERPHASE

  20. PLANT CELL PROPHASE

  21. PLANT CELL METAPHASE

  22. PLANT CELL ANAPHASE

  23. PLANT CELL TELOPHASE

  24. ANIMAL CELL INTERPHASE

  25. ANIMAL CELL PROPHASE

  26. ANIMAL CELL METAPHASE

  27. ANIMAL CELL ANAPHASE

  28. ANIMAL CELL TELOPHASE

  29. WHEN DOES MITOSIS OCCUR? G1 – normal cell functions S – DNA is copied G2 – normal cell functions Cell Cycle Movie In otherwords: Cells do a lot more than just reproduce!

  30. HOW LONG DOES MITOSIS TAKE? Bacteria – Human Kidney cells – Human Nerve cells – Onion Root Tip - Every 20 minutes! 24 hours Don’t divide after birth 720 minutes (12 hours)

  31. HOW LONG DOES MITOSIS TAKE? When does mitosis occur? All through life! When during life does mitosis occur the fastest? Before birth.

  32. # of cells in a phase Total # of cells 720 = Total time spent in that phase *

  33. Cancer – When Cell Cycle Doesn’t Stop • Cell Cycle Animation • Cell Cycle doesn’t always keep going • Checkpoints to make sure cycle is done correctly. Checkpoint Checkpoint Checkpoint

  34. What happens during a checkpoint? • Checkpoint #1 – During G1, Cdk checks if cell has grown enough. • Checkpoint #2 – End of G2, p27 checks if chromosomes have been copied. • Checkpoint #3 – During metaphase, p53 checks if chromosomes are lined up in middle of cell. Mutated p53 is most frequent cause of cancer.

  35. APOPTOSIS • If cell is too damaged, apoptosisor “programmed cell death” occurs. • What organelle might be involved in this process? LYSOSOME

  36. APOPTOSIS • When else during life does “programmed cell death” occur? Prior to birth

  37. CANCER • If cell cycle isn’t performed correctly, cells become cancerous. CANCER VIDEO

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