Final answer:
The cell division cycle in the fission yeast S.pombe is regulated primarily by the control of the checkpoints in the cell cycle.
Step-by-step explanation:
The cell division cycle in the fission yeast S.pombe is primarily regulated by the control of the checkpoints in the cell cycle. Checkpoints are internal controls that monitor the progression of the cell cycle and ensure that specific requirements are met before the cell advances to the next stage.
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. At these checkpoints, positive regulator molecules allow the cell cycle to advance, while negative regulator molecules monitor cellular conditions and can halt the cycle until specific requirements are met.