Control of the Cell Cycle

1. Control of the Cell Cycle Cancer

2. Objectives • Why do some types of cells divide rapidly, while others divide slowly? • What tells a cell when it is time to leave one part of the cell cycle and begin the next?

3. Proteins and enzymes control cell cycle • What controls the cell cycle: • Cyclins (protein) and a set of enzymes that attach to the cyclin and become activated • The interaction of these molecules based on the conditions in and out of the cell, control the cell cycle

4. Enzyme Production • Directed by genes on the chromosomes • What is a gene? • Segment of DNA that controls the production of protein • Many studies point to the portion of interphase just before DNA replication as the key control period in the cell cycle

5. What causes cancer? • Occasionally, cells lose control of the cell cycle • What causes them to lose control? • Failure of cell to produce certain enzymes • Overproduction of enzymes • Production of enzymes at the wrong time • Environmental factors • Cancer – malignant growth resulting from uncontrolled cell division

7. Lung Cancer

8. Cancer • Is caused by a mistake in the cell cycle • Currently, scientists consider cancer to be a result of changes in one or more of the genes that produce substances involved in controlling the cell cycle. • Changes are expressed as cancer when something prompts the damaged genes into action

10. Cancer • Cancerous cells form masses of tissue called tumors that deprive normal cells of nutrients. • In later stages, cancer cells enter the circulatory system and spread throughout the body (metastasis) • Form new tumors that disrupt the function of organs, organ systems and ultimately the organism

12. Cancer • 2nd leading cause of death in the US, exceeded only by heart disease • Can affect any tissue in the body • Most prevalent cancers in the US: lung, colon, breast and prostate

13. Causes of Cancer • Involve both genetic and environmental factors • Different cancers are more prevalent in different parts of the world • Environmental • Cigarette smoke, air and water pollution, exposure to UV rays from the sun • Genetic • Viral infections that damage the genes • Carrier of gene that makes you at higher risk (breast cancer: BRCA1, BRCA2 gene)

14. Cancer Prevention • Scientists have established a clear link between a healthy lifestyle and the incidence of cancer • Diets low in fat and high in fiber • Diets high in fat are linked to increased risk of breast, colon and prostate cancers • People who limit fat intake reduce their risk and also maintain a healthy body weight • High fiber diets linked to a reduced risk of colon cancer • Fruits, vegetables and grains = high fiber content • Vitamins and minerals may also help to prevent cancer • Keys in this category: caratenoids, Vit A, C & E, calcium • Caratenoids and Vit A yellow & orange vegetables, and green leafy vegetables • Vitamin C  citrus fruits • Vitamin E  SUN • Calcium  dairy products • Making healthy choices, exercising and avoiding carcinogens help to reduce your risk for cancer