Chapter 8: Mitosis - Cell Division and Reproduction
Chapter 8: Mitosis - Cell Division and Reproduction
Chapter 8: Mitosis - Cell Division and Reproduction
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<strong>Cell</strong>-Cycle Control System<br />
There are three critical points at which the cell<br />
cycle is controlled*:<br />
1. G1 Checkpoint: Prevents cell from entering S<br />
phase <strong>and</strong> duplicating DNA.<br />
Most important checkpoint.<br />
Amitotic cells (muscle <strong>and</strong> nerve cells) are frozen here.<br />
2. G2 Checkpoint: Prevents cell from entering<br />
mitosis.<br />
3. M Checkpoint: Prevents cell from entering<br />
cytokinesis.<br />
*<strong>Cell</strong>s must have proper growth factors to get<br />
through each checkpoint.