INTERPHASE

1
CHECKPOINTS STOP OR GO?
DNA checked, repaired enough organelles?
MITOSIS Cytokinesis
spindle attached?
?
?
duplicate organelles
G0
growth
INTERPHASE

INTERPHASE
?
SAV ratio? more cells needed? adequate
room?
replication
Biointeractive tutorial
Cells Alive
2
REGULATING THE CHECKPOINTS
proto-oncogenes trigger cell division, direct
cell to continue in the cycle turn on the
gas! tumor-suppressor genes shut down the
cycle hit the brakes!
3
EFFECTS OF MUTATIONS
In proto-oncogenes gt less division
therefore too few cells more division,
creating too many cells, increasing likelihood of
mutation In tumor-suppressor genes gt
loss of inhibition too many cells
creates TUMORS
Animation 1
4
More division increases likelihood of more
mutations What else causes mutations?
5
normal cells
Cells stop dividing when they should Cells die
when damaged
mutation gt cell death
cancer cells
Abnormal growth Abnormal DNA
6
TUMOR DIRECTS MORE GROWTH
Tumor that can grow and spread
tumor
angiogenesis
signals
blood vessel
Signal molecules
cell releases signal molecules that cause blood
vessels to grow
blood vessels bring in nutrients and removes
waste products
7
CANCER SPREADS via blood vessels
tumor breaches organ wall
1. Cancer cells invade surrounding tissues and
vessels
Blood vessel
cells lodge, grow in other organs
Metastasis
blood transports cancer cells
8
DIFFERENT TYPES OF CANCERSDIFFERENT TYPES OF
TREATMENTS

• Radiation use EM waves to disrupt tumor cell
  DNA
• Chemotherapy - toxic chemical cocktail
• problem both therapies kill mitotic cells,
  cancerous AND healthy
• Disrupt signal molecules produced by tumor cells
• Block growth of blood vessels to tumors
• Use immune system to attack cancer like it does a
  virus
• Vaccines for microbe-caused cancers (HPV)