29Cell DivisionEnds with one giant cell with two nuclei
30Cell Division Cytokinesis In animal cells: Cell membrane pinches inward between the two nucleiContinues pinching until two nuclei are separatedEnd up with about half the organelles and cytoplasm in each cell
37Enzymes that Control the Cell Cycle Controlled in large part by a group of enzymes called cyclinsCyclins: levels rise and fall during cycle causing numerous different actionsOther enzymes regulate specific phases of the cell cycleStill more enzymes: respond to events outside the cell and adjust the cell cycle
38Enzymes that Control the Cell Cycle Production of these enzymes is directed by DNAWhen DNA is damaged, production of enzymes goes all wrong:Complete lack of production of a enzymeOverproduction of a enzymeWithout the proper amount of specific enzymes the cell cycle will either stop (resulting in cell death) or cells will divide uncontrollably (resulting in cancer)
39Contact InhibitionSome cells will only divide if they are not in direct contact with one anotherWhen skin cells contact one another, cell division slows to rates just fast enough to replace cells that die due to normal wear and tearSkin cells sense contact through chemical signals, which are controlled by DNADamage to the DNA that controls these signals can also result in cancer
40CancerCancer: a disease where cells lose the ability to control the cell cycleCaused by changes to the DNA that controls enzymes that regulate the cell cycleMost small changes are fixed by the body, those that are not can become cancerCan begin in any cells of the body and then spread through the body in the bloodstream or lymphatic system (glands)
41CancerA quote from the American Cancer Society website:“Cancer is the second leading cause of death in the United States. Nearly half of all men and a little over one-third of all women in the US will develop cancer during their lifetimes. Today, millions of people are living with cancer or have had cancer.“The risk of developing most types of cancer can be reduced by changes in a person's lifestyle, for example, by quitting smoking and eating a better diet. The sooner a cancer is found and treatment begins, the better are the chances for living for many years.”
42Causes of Cancer The well-known factors that increase risk: Overexposure to UV radiation (THE SUN & SUN LAMPS!!)SmokingOver consumption of alcoholOther forms of radiationContaminants in waterViruses!
43Scare the Girls Slides Cervical Cancer Rates of cervical cancer have risen dramatically in young (16- to 30-year-olds) girls recentlyInfection with human papilloma virus (HPV) is found in nearly 80% of all cases of cervical cancerThere are 3,700 fatalities in the U.S. each year due to cervical cancerHPV is a sexually-transmitted disease!!!
44Scare the Girls Slides Cervical Cancer Routine screening (yearly gynecological exam) is the best way to catch the disease early.Vaccines are now available (Gardasil and Cervarix) to protect against HPV but it must be administered before a girl becomes sexually activeThere is no way to vaccinate or test males (who are carriers) and there is almost no way to tell whether a male is infected
45Scare the Guys SlideTesticular Cancer (aka “What Lance Armstrong had”)Testicular cancer is the most common cancer in American men between the ages of 15 and 40 (YOUR AGE GROUP!).7,600 men receive a diagnosis of testicular cancer each year in the US men dieWhen diagnosed early, testicular cancer is highly treatableRegular testicular self-examinations can help identify dangerous growths early, when the chance for successful treatment is highest