Final answer:
Major points of cell regulation are entry and exit from the cell cycle. Each step of the cell cycle is closely monitored by external signals and internal controls called checkpoints. Positive regulator molecules like the cyclins and Cdks allow the cell cycle to advance to the next stage; negative regulator molecules, such as tumor suppressor proteins, monitor cellular conditions and can halt the cycle until specific requirements are met.
Step-by-step explanation:
Major points of cell regulation are entry and exit from the cell cycle.
Each step of the cell cycle is closely monitored by external signals and internal controls called checkpoints. There are three major checkpoints in the cell cycle: one near the end of G₁, a second at the G₂/M transition, and the third during metaphase. Positive regulator molecules like the cyclins and Cdks allow the cell cycle to advance to the next stage; negative regulator molecules, such as tumor suppressor proteins, monitor cellular conditions and can halt the cycle until specific requirements are met.
Errors in the regulation of the cell cycle can cause cancer, which is characterized by uncontrolled cell division.