Why do Cells Divide?
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Why do Cells Divide?

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Why do Cells Divide? Why do Cells Divide? Presentation Transcript

  • Cells and SystemsWhy do cells divide?
  • Why do cells divide?
    because they cannot grow any larger
    to repair or replace damaged cells
    for reproduction or growth
  • Thinking with models
    Assume a cell is a cube
  • 6 μm2
    1 μm3
    6
    24 μm2
    8 μm3
    3
    96 μm2
    64 μm3
    1.5
  • As cell size increases, both the volume and surface area increase
    Volume increases at a faster rate – this is shown by a steeper slope on the trend line.
  • As cell size increases, the surface to volume ratio decreases
    This means that in larger cells there is not as much membrane surface area for the amount of cytoplasm as there is in smaller cells
  • Why Do Cells Divide? Think about . .
  • Why Do Cells Divide?
    Because the volume of a growing cell increases faster then its surface area
    Cells that grow too large no longer have enough surface area to take in nutrients and remove waste
    Cells that grow too large take longer to move materials within the cell
    As cells grow larger they become more inefficient
  • Why Do Cells Divide?
    Some cells die or are damaged, they must be replaced
    Multicellular organisms need to grow and develop, to do this requires more cells
  • How Do Cells Divide?
  • What is cancer?
    The cell cycle is a controlled process of growth and division
    Sometimes the control mechanisms break down. Usually this is due to a mutation in cell DNA
    Cancer is a disease that develops when this happens. Cells grow and divide uncontrollably. This can result in tumors and invasion of other healthy tissue.