1. 10-3 Regulating the Cell Cycle
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4. 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.
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5. Controls on Cell Division
Contact Inhibition
Cells in a petri dish will continue to grow until they come into contact with other cells.
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How can we see this happening in nature? (give some examples)
Cut in your finger (skin closing)
Broken bones (healing)
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Cell Cycle Regulators
How is the cell cycle regulated?
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Cell Cycle Regulators
Cell Cycle Regulators
The cell cycle is regulated by a specific protein.
The amount of this protein in the cell rises and falls in time with the cell cycle.
Scientists called this protein cyclin because it seemed to regulate the cell cycle.
Cyclins (which are enzymes) regulate the timing of the cell cycle in eukaryotic cells.
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Cell Cycle Regulators
Cyclins were discovered during a similar experiment to this one.
The timing of the cell cycle is regulated by cyclins. When cytoplasm from a cell in mitosis is injected into another cell, the second cell enters into mitosis. The reason for this effect is a protein called cyclin, which triggers cell division.
A sample of cytoplasm is removed from a cell in mitosis.
The sample is injected into a second cell in G2 of interphase.
As result, the second cell enters mitosis.
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Cell Cycle Regulators
Internal Regulators 
Proteins that respond to events inside the cell are called internal regulators.
Internal regulators allow the cell cycle to proceed only when certain processes have happened inside the cell.
An example of an internal regulator is an enzyme that is only produced when the all the chromosomes have duplicated or in anaphase when all the chromosomes are attached to the spindle fibers.
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Cell Cycle Regulators
External Regulators 
Proteins that respond to events outside the cell are called external regulators.
External regulators direct cells to speed up or slow down the cell cycle.
An example of an external regulator would be growth factors like growth hormones.
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13. 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?
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14. Uncontrolled Cell Growth
Cancer cells do not respond to the signals that regulate the growth of most cells.
Cancer cells have a mutation in their DNA (p53 gene most defective in cancer cells)which causes them to not make the correct enzymes that inhibit cell division. This allows these cells to continue mitosis uncontrollably. They DO NOT STOP dividing!!!!!
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15. Uncontrolled Cell Growth
Cancer cells divide uncontrollably and form masses of cells called tumors that can damage the surrounding tissues. They start starving the normal cells around the tumor by stealing all the nutrients and can cause the normal tissues to die off eventually causing organs to fail.
Cancer cells may break loose from tumors and spread throughout the body (metastasis), disrupting normal activities and causing serious medical problems or even death.
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Cancer is the 2nd leading cause of death in the US. Cancers that are common in the US are; lung, breast, prostate and colon. Causes of cancer are difficult to pinpoint because both environmental and genetic factors are involved.
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Cancer Treatments
Surgery – removing the tumor
Chemotherapy – killing the cells that divide rapidly
Radiation – killing the cancer cells
4. Immunotherapy – using your own immune system
5. Targeted Therapy – stop cancer cells from growing, stop blood supply, highlight cancer cells to the immune system.
6. Hormone Therapy – slows the growth of cancer
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Preventions –
not smoking
diet (low-fat and high-fiber)
vitamins and minerals (carotenoids, A, C, E and Calcium)
Exercise
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