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

2. 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 respond by not growing. This demonstrates that controls on cell growth and division can be turned on and off.

3. End Show Slide 3 of 18 10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall Controls on Cell Division Contact Inhibition: Cells in a petri dish will continue to grow until they come in contact with other cells

4. End Show Slide 4 of 18 10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall Cell Cycle Regulators Cyclin: Protein that regulates the timing of the cell cycle. The amount of cyclin in the cell rises and falls in time with the cell cycle.

5. End Show Slide 5 of 18 10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G 2 of interphase. As result, the second cell enters mitosis. Cyclins were discovered during an experiment like this. Cell Cycle Regulators

6. End Show Slide 6 of 18 10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall Internal Regulators 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

7. End Show Slide 7 of 18 10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall Cell Cycle Regulators External regulators: Proteins that respond to events outside the cell. External regulators direct cells to speed up or slow down the cell cycle.

8. End Show 10-3 Regulating the Cell Cycle Slide 8 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. Cancer cells do not respond to the signals that regulate the growth of most cells.

9. End Show Slide 9 of 18 10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall Uncontrolled Cell Growth Tumors: Cancer cells divide uncontrollably and form masses of cells that can 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.

10. End Show - or - Continue to: Click to Launch: Slide 10 of 18 Copyright Pearson Prentice Hall 10-3

11. End Show Slide 11 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.

12. End Show Slide 12 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.

13. End Show Slide 13 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.

14. End Show Slide 14 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.

15. End Show Slide 15 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.

16. END OF SECTION