Download 5.3 Regulation of the Cell Cycle

5.3 Regulation of the Cell Cycle
KEY CONCEPT
Cell cycle regulation is necessary for healthy
g
growth.
5.3 Regulation of the Cell Cycle
I t
l and
d external
t
l factors
f t
l t cell
ll division.
di i i
Internal
regulate
• External factors include physical and chemical signals.
– Messages
from
nearby
M
f
b cells
ll or distant
di t t parts
t off the
th
body.
• Growth factors are proteins that stimulate cell division.
– Activate genes that trigger cell growth
– Most mammal cells form a single layer in a culture
dish and stop dividing once they touch other cells
(phenomenon).
5.3 Regulation of the Cell Cycle
• Two of the most important internal factors are kinases
and cyclins.
– Help a cell advance to different stages of the cell
cycle when the cells bind to each other.
• External factors trigger internal factors
factors, which affect the
cell cycle.
5.3 Regulation of the Cell Cycle
• Apoptosis is programmed cell death.
– a normal feature of healthy organisms
– caused
db
by a cell’s
ll’ production
d ti off self-destructive
lf d t ti
enzymes
– occurs in
webbed fingers
development
of infants
5.3 Regulation of the Cell Cycle
C ll di
i i is
i uncontrolled
t ll d in
i cancer.
Cell
division
• Cancer cells form disorganized clumps called tumors.
– Benign tumors remain clustered and can be removed.
– Malignant tumors metastasize, or break away, and can
form more tumors.
tumors
normal cell
cancer cell
bloodstream
5.3 Regulation of the Cell Cycle
• Cancer cells do not carry out necessary functions.
• Cancer cells come from normal cells with damage to
genes involved in cell-cycle regulation.
5.3 Regulation of the Cell Cycle
• Carcinogens are substances known to promote cancer.
• Standard cancer treatments typically kill both cancerous
and healthy cells.
• Example: Chemo Therapy, Radiation.