10-3 Regulating the Cell Cycle Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall
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. Copyright Pearson Prentice Hall
Controls on Cell Division Contact Inhibition Cells in a petri dish will continue to grow until they come into contact with other cells. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall How can we see this happening in nature? (give some examples) Cut in your finger (skin closing) Broken bones (healing) Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Cell Cycle Regulators How is the cell cycle regulated? Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 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. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 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. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 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. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 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. Copyright Pearson Prentice Hall
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? Copyright Pearson Prentice Hall
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!!!!! Copyright Pearson Prentice Hall
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. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 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. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall
Copyright Pearson rentice Hall 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 Copyright Pearson rentice Hall
Copyright Pearson Prentice Hall Preventions – not smoking diet (low-fat and high-fiber) vitamins and minerals (carotenoids, A, C, E and Calcium) Exercise Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall
END OF SECTION