1. Regulating the Cell Cycle (10.3)

2. Controls on Cell Division
Cells are prone to dividing, but they are regulated (to divide or not to divide)
Cyclin: protein that regulates the cell cycle or tells the cell to divide or not divide
Regulatory Proteins
Internal Regulators
External Regulators
Proteins that regulate cell division from within the cell
Proteins that regulate cell division from outside the cell (growth factors)
They only allow cell division to occur if the cell is ready  DNA copied
Direct cells to speed up or slow down cell division
Ex: telling a cell not to divide due to the DNA not replicating
Ex: wound healing would need cell division to speed up

3. Apoptosis Cells are produced everyday and cells die every day
Two ways to cell death:
damage or injury to the cell
programmed death (apoptosis) → the cell undergoes a series of steps leading to cell destruction
Apoptosis Steps
the cell and the chromatin shrink
the cell membranes breaks into parts
Neighboring cells clean up the dead cell’s remains

4. Caner: Uncontrolled Cell Growth
Cancer: a disorder in which body cells lose the ability to control growth
they do not respond to the signals that regulate cell growth → uncontrollable growth
tumor: mass of cancer cells
Two Types of Tumors
Benign: noncancerous tumors that do not spread through the body
Malignant: cancerous tumors that invade and destroy healthy tissue
they absorb nutrients needed by other cells, block nerve connections, and prevent the organs they invade form functioning properly

5. Growth of Cancer

6. What Causes Cancer?
Cancer is caused by defects in genes that regulate cell growth
Sources:
smoking/chewing tobacco
radiation exposure
other defective genes
viral infections
Defective gene p53 cause cells to lose information needed to respond to signals that normally control their growth

7. Treatments for Cancer Surgery
Melanoma, skin cancer, can be removed by surgery but only if spotted early
Radiation
Since cells grow rapidly and need to copy their DNA, this makes them vulnerable to radiation
Chemotherapy
chemical compounds that kill cancer cells or slow their growth
Since they target rapidly dividing cells, this treatment can be harmful to natural cell division