Control of the Cell Cycle

1
Control of the Cell Cycle
2
Division Rates

• Different cells divide at different rates
• This is because different cells have different
  functions which requires them to divide at
  different times at different frequencies

3
Enzymes control the Cell Cycle

• The production of certain enzymes is what causes
  cells to progress through the cell cycle.
• Some enzymes function in initiating cells
  through the process others function in actually
  inhibiting promotion to the next step.
• Enzyme production is directed by genes located
  on chromosomes
• A Gene ? segment of DNA that controls the
  production of a protein (ALL enzymes are proteins)

4
Contact Inhibition

• CONTACT INHIBITION type of cell-to-cell
  communication that tells cells when to stop
  growing
• Normal cells will stop growing when they dont
  have anything to attach to anymore
• Abnormal cells will not stop growing when they
  run out of attachment sites, instead they will
  grow over and on top of each other

5
Cancer

• Cancer is cell death or the uncontrolled
  division of cells
• can result from either the failure to produce
  certain enzymes or the overproduction of certain
  enzymes
• thought to be caused by changes in one or more
  genes that are in control of producing enzymes
  involved in the cell cycle
• there are some environmental and genetic factors
  that also may cause cancer
• Tumors ? masses of tissue that may deprive
  normal cells of their nutrients