Regulation of the Cell Cycle Regulating Division Division

Regulation of the Cell Cycle

Regulating Division • Division is regulated by physical and chemical factors. – Physical: cells stop dividing when they touch other cells. – p 53: protein that blocks cell division if the DNA is damaged. Mutation in this protein often causes cancer.

Apoptosis • Programmed cell death. – caused by production of destructive enzymes – occurs in development of infants.

Cancer: Good Cells Gone Bad • Uncontrolled cell growth – May divide quickly and indefinitely • Occurs when the genes involved in cell-cycle regulation are damaged. • Cells do not carry out necessary functions, often damage healthy tissue.

What Causes Cancer? • Carcinogens: agents known to cause cancer. –Ex: gasoline, cigarettes • Radiation • Random genetic mutations

Cancer Terms • Benign tumors grow slowly and are encapsulated (can be removed easily). • Malignant tumors are invasive, grow fast, and often metastasize. • Metastasis: cancer cells move from one organ or tissue to another.

Curing Cancer • Radiation and chemo kill all dividing cells (including healthy cells) • How chemo drugs work – Some work by stopping DNA replication – Some inhibit spindle fiber formation (= no mitosis) – Some stop blood vessel formation to tumor (no blood = tumor dies).

The real reason dinosaurs became extinct