5.3 Regulation of the Cell Cycle

KEY CONCEPTCell cycle regulation is necessary for healthy growth.

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.

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 stages of the cell cycle

• External factors trigger internal factors,

which affect the cell cycle.

5.3 Regulation of the Cell Cycle

– a normal feature of healthy organisms– caused by a cell’s production of self-destructive

enzymes– occurs in

developmentof infants

webbed fingers

• Apoptosis is programmed cell death.

5.3 Regulation of the Cell Cycle

Cell division is uncontrolled in cancer.

• Cancer cells form disorganized clumps called tumors.

cancer cellbloodstream

normal cell

– Benign tumors remain clustered and can be removed.– Malignant tumors metastasize, or break away, and can

form more tumors. (noun = metastasis)

5.3 Regulation of the Cell Cycle

Different growth patterns of tumors

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.– UV radiation– Smoking– Other forms of radiation (nuclear radiation, x-rays,

etc.)• Standard cancer treatments typically kill both cancerous

and healthy cells.

5.3 Regulation of the Cell Cycle

Viruses can also cause cancer!

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.

5.3 Regulation of the Cell Cycle

How are cancers named? First site of origin: