10-3 Regulating the Cell Cycle

Cyclins are proteins that regulate the cell cycle– “Tell” cell when to divide, enter cell cycle phases– Signal spindle formation during Interphase– In addition to cyclins, other proteins also help regulate cycle

Internal regulators respond to events inside a cell - check that a cell is prepared for mitosis – spindle fibers, replicated DNA, etc.

External regulators are outside signals to speed up/slow down cell division– ie: contact inhibition, wound healing

Contact InhibitionMost cells will keep dividing until they come in contact with other cells

What is Cancer?Result of faulty cell cycle– Cells lose ability to control

growth – do not respond to regulatory signals

– Cells divide out of control – do not spot dividing when come in contact with other cells like normal cells do

– Demonstrate bizarre behavior

What is Cancer?Malignant tumor– Lump resulting from

division of cancer cell• Can spread• Displaces normal tissue• Can spread into

circulatory system

Metastasis– Spread of malignant

cells to other tissuesCancers named for where they originate

• Non-metastatic, noninvasive tumors are called benign

What causes Cancer?Causes of cancer– Carcinogens – cancer

causing chemicals (tobacco, asbestos)

– Mutations in DNA overproduce growth factors (cells keep dividing) OR do not produce suppressors (cells never stop dividing) - a defect in p53 gene

– Some viruses– Heredity - genes– Radiation

Symptoms/Treatments

Symptoms vary – Unexplained weight change– Lumps or growths– Abnormal bleeding

Treatment– Prevention! (diet, lifestyle, self-examinations)– Surgery/Radiation/Chemotheraphy

Cancer Treatments

GOAL: Stop cells from dividing!– Surgery – remove the cells/tumor– Radiation

• High energy radiation disrupts cell division

– Chemotherapy• Drugs that disrupt cell division• Anti-mitotic drugs (taxol, vinblastine)