5.3 Regulation of the Cell Cycle Internal and external factors regulate cell division. External factors include physical and chemical signals. Growth factors are proteins that stimulate cell division. –Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

13.1 Ecologists Study Relationships BellWORK!!!! Do it now. What is it called when some cells in your body won’t stop dividing (mitosis). Hint: it kills 12% of humans worldwide.

5.3 Regulation of the Cell Cycle CANCER when cells divide and grow uncontrollably, forming tumors and invading the body.

5.3 Regulation of the Cell Cycle Apoptosis is when cells die automatically/normally

5.3 Regulation of the Cell Cycle Cell division is uncontrolled in cancer. cancer cell bloodstream normal cell When cancer cells enter the blood, it spreads through the body (metastacizes). This is VERY bad.

5.3 Regulation of the Cell Cycle Symptoms Vary widely “The Great Imitator”

5.3 Regulation of the Cell Cycle Tumors are lumps of cancer cells Two Types 1. Benign tumors remain clustered and can be removed. 2. Malignant tumors metastasize (spread)

5.3 Regulation of the Cell Cycle About half of people who get treatment for malignant cancer die from it

5.3 Regulation of the Cell Cycle What causes cancer? causes of cancer are diverse, complex, and only partially understood. Things known to increase risk (carcinogens): Tobacco use Radiation Laziness Obesity Pollution The Sun

5.3 Regulation of the Cell Cycle How to avoid cancer: Don’t smoke cigarettes Don’t drink alcohol Exercise 3-5 times per week Eat vegetables, fruit, and fish Avoid red meat (cows)

5.3 Regulation of the Cell Cycle Curing Cancer Cancer is a class of diseases –There will probably never be one “cure” We still do not know: –What, exactly, causes cells to become cancerous? –How, exactly, do cancer cells work? Focus on prevention. So, be a doctor, and help figure it out!