AP Biology / Unit 4: Cell Communication and Cell Cycle
4.6 Regulation of the Cell Cycle
Notes
Checkpoints (G₁, G₂, M) check for problems. Cyclins and cyclin-dependent kinases (CDKs) drive progress.
- Tumor suppressors (like p53) stop the cycle; proto-oncogenes push it forward.
- Uncontrolled division can lead to cancer; apoptosis removes damaged cells.
Practice
CDKs are active when bound to:
Cyclin levels rise and fall.
The M checkpoint makes sure:
Spindle checkpoint.
A mutation that disables p53 can lead to cancer because:
Loss of a tumor suppressor.
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