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Mitosis & Cancer:When Making New Cells
Goes Terribly Wrong!
If we want to cure cancer… We must understand what causes it.
This means understanding the cell cycle.
When is mitosis a good thing?1) When you have to add or replace cells
growth & development repair replacement
Checkpoints2) There are strict checkpoints in the cell cycle to ensure that each stage does not start before the last one finished
Checkpoint in Interphase: S phase to make sure that DNA was replicated correctly
When is mitosis a BAD thing3) When cells reproduce & they are not needed
these cells take over organs, but don’t do the right job
they just keep making copies cancer
damages organs
What is cancer4) Cancer is a disorder in which some of the body’s own cells lose the ability to control growthCancer cells do not respond to the signals that regulate the growth of most cells
How do the cells turn bad? The timing of the cell cycle is regulated by
cyclins (proteins) Cyclins trigger cell division
For example: p53 gene regulates the process that leads the cell into mitosis
Conditions have to be right for the cell to divide
5) Gene proto-oncogenes encourage cell division in normal healthy cells
6) Tumor suppressor genes inhibit cell division
Why would cells just make copies?
7) If DNA gets damaged, cells stop listening to correct instructions
mutations
Causes of mutations: UV radiation chemical exposure radiation exposure heat
cigarette smoke pollution age genetics
8) Cells gone bad… If the proto-oncogene is damaged then
cells can either never divide or divide uncontrollably creating a tumor
If the tumor-suppressor gene gets damage it may never tell the cell to stop dividing and the cell will divide and divide creating a tumor
Tumors9) Benign tumor
abnormal cells remain at original site as a lump
most do not cause serious problems &can be removed by surgery
Tumors10) Malignant tumor
cells leave original site carried by blood system to other tissues start more tumors
damage functions of organs throughout body
Treatments for cancers11) Treatments kill rapidly dividing cells
chemotherapy poisonous drugs that kill rapidly dividing cells
radiation high energy beam kills rapidly dividing cells
side effects
2009-2010
Any Questions??
Any Questions??