Section 10.3 (Pg. 286-290):Regulating the Cell Cycle

Controlling Cell Division

- Uses proteins inside and outside the cell

- Cyclins– Regulate the timing of the cell cycle

- Internal regulators– Allow the cell cycle to proceed only

when certain events have occurred

Controlling Cell Division- External regulators

– Can speed up or slow down the cell cycle– Growth factors stimulate growth and

division of cells– Other proteins can cause cells to stop

dividing once they fill a space

- Apoptosis– Is controlled cell death– Destroys malfunctioning cells– Can shape a growing embryo

Too Much Apoptosis

Cancer- Cells do not respond to signals that regulate cell

growth– Cells divide uncontrollably

- These cells form a tumor– Benign tumors do not spread to healthy tissue– Malignant tumors take over and destroy healthy

tissue

- Metastasis– When cancer cells break off a tumor, travel to other

parts of the body, and form more tumors

Causes of Cancer

- Exposure to toxic chemicals, radiation, and some viruses

- Results in defective or mutated DNA– Damage to genes that control cell

growth can cause a tumor– Damage to the p53 gene is a

common cause of many cancers

Treatment for Cancer - Surgery

– Physically remove tumor

- Radiation– Mutate tumor cells’ DNA to make them

nonfunctional

- Chemotherapy– Administer chemicals that kill tumor cells

or slows their growth– Can also interfere with cell division in

healthy cells, producing side effects