Download Cancer Notes

Control of the
Cell Cycle
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
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)
Contact Inhibition
 CONTACT INHIBITION = type of
cell-to-cell communication that tells cells when
to stop growing
 Normal cells will stop growing when they
don’t 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
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