Question

What are the locations in the cell cycle where proteins can initiate or stop the next phase of the cycle called?

Answer 1

A checkpoint is one of several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable.

Explanation: Or

Oscillations in the activities of various cyclin-Cdk complexes leads to the initiation of various cell-cycle events. Thus, activation of S-phase cyclin-Cdk complexes initiates S phase, while activation of M-phase cyclin-Cdk complexes triggers mitosis.