End Show Slide 1 of 18 Copyright Pearson Prentice Hall 10-3 Regulating the Cell Cycle

End Show 10-3 Regulating the Cell Cycle Slide 2 of 18 Copyright Pearson Prentice Hall Controls on Cell Division Experiments show that normal cells will reproduce until they come into contact with other cells: When cells come into contact with other cells, they stop growing. cell growth and division can be turned on and off.

End Show Slide 3 of Regulating the Cell Cycle Copyright Pearson Prentice Hall Controls on Cell Division Contact Inhibition

End Show 10-3 Regulating the Cell Cycle Slide 4 of 18 Copyright Pearson Prentice Hall Cell Cycle Regulators How is the cell cycle regulated? –Cyclins regulate the timing of the cell cycle in eukaryotic cells.

End Show Slide 5 of Regulating the Cell Cycle Copyright Pearson Prentice Hall Internal Regulators Allow the cell cycle to proceed only when certain processes have happened inside the cell. Example: p53 Gene that regulates the passage into mitosis Cell Cycle Regulators

End Show Slide 6 of Regulating the Cell Cycle Copyright Pearson Prentice Hall Cell Cycle Regulators External Regulators Proteins that respond to events outside the cell. Direct cells to speed up or slow down the cell cycle.

End Show 10-3 Regulating the Cell Cycle Slide 7 of 18 Copyright Pearson Prentice Hall Uncontrolled Cell Growth Cancer is a disorder in which some of the body's own cells lose the ability to control growth. How are cancer cells different from other cells? –Cancer cells do not respond to the signals that regulate the growth of most cells.

End Show Slide 8 of Regulating the Cell Cycle Copyright Pearson Prentice Hall Uncontrolled Cell Growth Cancer cells: –divide uncontrollably –form masses of cells: tumors –Tumors damage the surrounding tissues. Cancer cells may break loose from tumors and spread throughout the body, disrupting normal activities and causing serious medical problems or even death.

End Show Slide 9 of 18 Copyright Pearson Prentice Hall 10-3 The cell cycle is believed to be controlled by proteins called a.spindles. b.cyclins. c.regulators. d.centrosomes.

End Show Slide 10 of 18 Copyright Pearson Prentice Hall 10-3 Proteins that respond to events inside the cell are called a.internal regulators. b.external regulators. c.cyclins. d.growth factors.

End Show Slide 11 of 18 Copyright Pearson Prentice Hall 10-3 Once a multicellular organism reaches adult size, the cells in its body a.stop dividing. b.grow and divide at different rates, depending on the type. c.have the same life span between cell divisions. d.undergo cell division randomly.

End Show Slide 12 of 18 Copyright Pearson Prentice Hall 10-3 One effect of an internal regulator is that a cell will not begin mitosis until a.it becomes too large. b.the cell’s growth is stimulated. c.it is in physical contact with other cells. d.all its chromosomes have been replicated.

End Show Slide 13 of 18 Copyright Pearson Prentice Hall 10-3 One factor common to almost all cancer cells is a.a lack of cyclin. b.a defect in gene p53. c.exposure to tobacco smoke. d.exposure to radiation.