1. Cell Cycle Controls Biology 3 Kawashima Philippine Science High School SY 2009-2010

2. Key Terms and Concepts Checkpoints Cyclins Cyclin-dependent kinases

4. G1 Checkpoint Also known as “Restriction Point” in mammalian cells Cells that go through G1 usually complete the cell cycle Cells that do not receive the go-signal exit the cell cycle Quiescent non-dividing stage called G0 phase

5. G1 checkpoint Continue with G1 and proceed to S Exit cycle; switch to nondividing state

6. G2 Checkpoint MPF or maturation promoting factor drives the cell past the G2 checkpoint MPF is a protein complex composed of cyclins and cyclin-dependent kinases (Cdk) Accumulated cyclin in G2 associate with cyclin-dependent kinases

9. M Phase Checkpoint Ensures that chromosomes are properly attached to mitotic spindle (composed of microtubules) Anaphase promoting complex (APC) is inactive until kinetochores have interacted with microtubules Activation of APC indirectly triggers breakdown of cyclins

13. External Signals Affect Regulation