Regulating the Cell Cycle and Cancer Ms. Cohen

Controls on Cell Division Cells will grow if given ample food and space They stop when they reach other cells What happens when you get a cut? Food and room

Cell Cycle Regulators Cyclins and proteins regulate the timing of the cell cycle in eukaryotic cell. Cyclins were disovered in the 1980s. By injecting nondividing cells with cyclin protein, cells started making a mitotic spindle Cyclins and proteins regulate the timing of the cell cycle.

Regulators Internal regulators are proteins that respond to events inside the cell. Allow cell to proceed when certain processes have occurred inside. External regulators are proteins that respond to events outside the cell. Direct cells to speed up or slow down the cell cycle.

Uncontrolled Cell Growth Cancer cells do not respond to the signals that regulate the growth of most cells. Divide rapidly Form masses called tumors Cancer cells may break loose from tumors and spread. Breast cancer cells forming in a duct

What causes cancer? Defects in regulatory genes Smoking, radiation, viral infections, chewing tobacco Defective p53 gene Smoking tobacco, viral infection, radiation exposure Defect in gene p53

P53 gene on Chromosome 17 The p53 gene is responsible for proteins that can either repair damaged cells, or cause damaged cells to die, a process called apoptosis. When the gene is not working due to a mutation, these proteins that repair cells or eliminate damaged cells are not produced, and abnormal cells are allowed to divide and grow. This is one way in which HPV causes cervical cancer…by turning off the p53 gene thus not allowing for apoptosis. Gene therapy is being used to kill cancer cells when p53 does not work to kill cells.