1. 5.3 Regulation of the Cell Cycle
KEY CONCEPT
Cell cycle regulation is necessary for healthy
growth.

2. 5.3 Regulation of the Cell Cycle
Internal and external factors regulate cell division.
• External factors include physical and chemical signals.
• Growth factors are proteins that stimulate cell division.
– Most mammal cells form a single layer in a culture dish
and stop dividing once they touch other cells.

3. 5.3 Regulation of the Cell Cycle
• Two of the most important internal factors are kinases
and cyclins.
– Cyclin: group of proteins that triggers action of
kinases
– Kinase: enzymes that affect molecule’s activity
- kin = Kinetics, kinein = “to move”
- ase = enzyme
– Together these both help a cell advance to different
External
stages of the cell cycle
growth
factors
• External factors trigger internal factors,
Triggered
which affect the cell cycle.
cell cycle
Cyclins
activities
Kinases

4. 5.3 Regulation of the Cell Cycle
• Apoptosis is programmed cell death.
– a normal feature of healthy organisms
– caused by a cell’s production of self-destructive
enzymes
– occurs in
webbed fingers
development
of infants

5. 5.3 Regulation of the Cell Cycle
Cell division is uncontrolled in cancer.
• 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. (noun = metastasis)
normal cell
cancer cell
bloodstream

6. 5.3 Regulation of the Cell Cycle
Different growth patterns of tumors

7. 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.

8. 5.3 Regulation of the Cell Cycle
• Carcinogens are substances known to promote cancer.
– UV radiation
– Smoking
– Other forms of radiation (nuclear radiation, x-rays,
etc.)
• Standard cancer treatments typically kill both cancerous
and healthy cells.

9. 5.3 Regulation of the Cell Cycle
Viruses can also cause cancer!

10. 5.3 Regulation of the Cell Cycle
How are cancers named? Type of tissue of origin:
• Carcinoma: tumor of the internal or external lining of the
body (skin & covering and lining of organs and internal
passageways).
• Sarcoma: cancer that originates in supportive and
connective tissues such as bones, tendons, cartilage,
muscle, and fat.
• Leukemias("liquid cancers" or "blood cancers") are
cancers of the bone marrow (the site of blood cell
production).
• Lymphomas develop in the glands or nodes of the
lymphatic system, a network of vessels, nodes, and
organs.

11. 5.3 Regulation of the Cell Cycle
How are cancers named? First site of origin: