1. Unit 5: Cell Growth and Development 5.3 Control of the Cell Cycle

2. Not all cells move through the cell cycle at the same rate.
Example: Most nerve cells do not divide once they are developed
Example: Blood cells may complete a cycle every few hours
Not all cells move through the cell cycle at the same rate.

3. The cell cycle is controlled by cyclins and other proteins
Internal regulatory proteins: Proteins that allow the cell cycle to proceed only when certain events have occurred within the cell
Cyclin: A type of protein that regulates the cell cycle
Regulatory Proteins

4. The cell cycle is controlled by cyclins and other proteins
External regulatory proteins: Proteins that respond to events outside the cell to speed up or slow down the cell cycle
Growth factors: A type of protein that stimulates growth and division of cells during embryonic development and wound healing
Regulatory Proteins

5. Cell growth and division is controlled by proteins and 3 checkpoints
Cell Growth (G1) Checkpoint:
If the cell is healthy and large enough, it will divide.
If conditions are not favorable, it will not divide
DNA Synthesis (G2) Checkpoint:
DNA replication is checked by DNA repair enzymes
Once checked, cell will prepare for mitosis
Mitosis Checkpoint:
Triggers the exit of Mitosis and the entering of G1 (Growth Stage 1).
Cell growth and division is controlled by proteins and 3 checkpoints

6. As new cells are produced, many others must die
As new cells are produced, many others must die. This happens in two ways:
By accident, due to damage or injury to a cell
“Programmed” to die

7. Apoptosis: A series of controlled steps leading to the self- destruction of a cell that has been programmed to die.
Apoptosis plays a key role in development by shaping the structure of tissues and organs in plants and animals.

8. The human hand is shaped the way it is because cells between the fingers die by apoptosis during tissue development
Example

9. Cancer
Uncontrolled cell growth
Caused by defects in the genes

10. Cancer and the Cell Cycle Discussion Questions
Explain the factors that control normal cell division.
Explain what happens when normal cell division is disrupted.
Compare and contrast the terms carcinogen and mutagen.
Use the terms TUMOR SUPPRESOR GENES, PROTONCO GENES, and MUTATION to explain how the cell cycle relates to cancer.
Cancer and the Cell Cycle Discussion Questions