Download 5.3 Regulation of the Cell Cycle

5.3 Regulation of the Cell Cycle
KEY CONCEPT
Cell cycle regulation is necessary for healthy
growth.
5.3 Regulation of the Cell Cycle
Internal and external factors regulate cell division.
• Internal factors:
– External factors trigger internal factors, which
affect the cell cycle
– Two of the most important internal factors are
kinases and cyclins.
- Kinase-enzyme that, when activated, transfers a
phosphate group from one molecule to a specific target
molecule, changing its shape. Activated by cyclins.
- Cyclins are a group of proteins that are rapidly made and
destroyed at certain points in the cell cycle. These two
factors help a cell advance to different stages of the cell cycle
5.3 Regulation of the Cell Cycle
Internal and external factors regulate cell division.
• External factors include physical and chemical
signals.
– Physical:
- cell-cell contact
· Most mammal cells form a single layer in a culture dish
and stop dividing once they touch other cells.
– Chemical:
- Growth factors are proteins that stimulate cell division.
5.3 Regulation of the Cell Cycle
• Carcinogens are substances known to promote
cancer.
– Ex: tobacco smoke, air pollutants, radiation, and
even some mutated genes carried by viruses.
5.3 Regulation of the Cell Cycle
Cancer cells
• Characterized by uncontrolled cell division.
– Continue to grow despite cell-cell contact or lack of
growth factors.
• Standard cancer treatments typically kill both cancerous
and healthy cells.
normal cell
cancer cell
bloodstream
5.3 Regulation of the Cell Cycle
Cancer cells
• Cancer cells form disorganized clumps called tumors.
– Do not carry out specialized functions needed by the
body.
– Benign tumors remain clustered and can be removed.
– Malignant tumors metastasize, or break away, and can
form more 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
• Apoptosis is programmed cell death.
– a normal feature of healthy organisms by ridding
the body of unhealthy cells.
– caused by a cell’s production of self-destructive
enzymes
– occurs in
webbed fingers
development
of infants
- EX: cells
between
fingers.
5.3 Regulation of the Cell Cycle
YOU HAD A TAIL…AND GILL SLITS!!!
5.3 Regulation of the Cell Cycle
YOU HAD A TAIL…AND GILL SLITS!!!