1. Regulations to Cell Cycle
External Factors (outside cell)
Cell to cell contact- physical
Growth factors (proteins)- chemical
Ex. Platelets store growth factor that triggers growth of cells to repair wounds/stop bleeding

2. Internal Factors (Inside Cell)
*External factors trigger internal factors, which affect the cell cycle.
*2 main internal factors: kinases & cyclins (proteins)
Examples of cell regulation:
Apoptosis- Programmed cell death; “cell suicide”.
(Nucleus shrinks, breaks apart, and is recognized by immune system)
Ex. Child development- webbing between fingers

3. webbed fingers

4. Cancer- Uncontrolled cell division
Cancer- Uncontrolled cell division. *Cancer cells continue to divide even when surrounded by other cells! (disorganized clumps of cells= tumors) 2 Types of Tumors: 1)Benign- Cells remain clustered; harmless 2) Malignant- Cells break away (metastasize) and form other tumors; harmful

5. bloodstream
normal cell
cancer cell

6. Where do cancer cells come from?
Cancer cells come from normal cells that have suffered damage to genetic information
Sometimes this is inherited; sometimes this comes from carcinogens (like sunlight & tobacco smoke)
Why are tumors/cancer cells harmful?
Cancer cells do not perform the specialized functions of normal cells.
They require food and oxygen just as normal cells
They exert pressure on surrounding organs

7. Treatment Radiation (localized) Surgery (localized)
Chemotherapy (Drugs travel through whole body)