KEY CONCEPT Cell cycle regulation is necessary for healthy growth.

1. KEY CONCEPTCell cycle regulation is necessary for healthy growth.

2. Internal factors • kinases change the activity of other molecules by adding a phosphate group • cyclins –are rapidly made and destroyed at different points of the cell cycle. This helps cells advance to different stages of the cells cycle. External factors • cell to cell contact • growth factors which stimulate internal factors that affect the cell cycle (cell division)

3. 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.

4. Carcinogens are substances known to promote cancer. • Ex. Air pollution, tobacco smoke, mutated genes carried by viruses. • Standard cancer treatments typically kill both cancerous and healthy cells.

5. Cancer cells do not carry out necessary functions. • Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

6. normal cell cancer cell bloodstream Cell division is uncontrolled in cancer. • Cancer cells form disorganized clumps called tumors-disorganized clumps of cancer cells that do not carry out normal functions • Benign tumors remain clustered and can be removed. • Malignant tumors metastasize, or break away, and can form more tumors.

7. webbed fingers • Apoptosis is programmed cell death. • a normal feature of healthy organisms • caused by a cell’s production of self-destructive enzymes 1.occurs indevelopmentof infants 2.Helps rid the body of unhealthy cells