Regulating Cell Cycle & Cancer

10-3 pgs. 250-252

Regulating the Cell Cycle

• Cells start and stop dividing due to environmental factors.

• The cell cycle can be turned “on and off”• Controlled by a group of proteins known as cyclins– 2 types• Internal Regulators- G1 Restriction Point• External Regulators- embryonic development and

wound healing

Restriction Points

Uncontrolled Cell Growth/Cancer

A. Cancer is the uncontrolled growth and dividing of cells.

B. There are over 100 types of cancer.

1. Each type of cancer is named for the type of cells where the cancer started.

i.e. Skin cancer starts in skin cells. Lung cancer in lung cells.

How Does Cancer Spread?• As cells begin to divide at an uncontrolled rate, a tumor begins to form.

– A tumor is a clump of cancerous cells.

• There are two types of tumors:

– Benign - A tumor that doesn’t spread.

– Malignant - A tumor that can spread to other parts of the body.

• Some cells can break off from a malignant tumor, enter the bloodstream, and spread the cancer.

– The spreading of cancer is called metastasize

What Causes Cancer?• Genetic Predisposition.

• Country of origin

– Breast cancer is high in the U.S. but low in Japan.

– Stomach cancer is high in Japan but low in the U.S.

• Environmental Factors

– Exposure to secondhand smoke.

– Exposure to UV rays from sunlight.

– Air & water pollution.

Carcinogens

• Any cancer causing agents– Cigarettes– UV Sunlight– “Hazardous chemicals” such as gasoline.– Diet– Alcohol– Pollution

Treatment

• 3 Main forms of treatment• Radiation- exposing cancer cells to radiation.– Kills cancer cells but also impacts non-cancerous

cells.• Chemotherapy- Pharmaceuticals which target

fast dividing cells.– Attacks both cancerous and non-cancerous cells

which divide quickly• Surgery- removal of tumor