Question

What are the checkpoints in cell cycle?

Answer 1

Hint: Checkpoints here simply refers to the site or the locations where the cell is analyzed internally as well as externally to determine or decide whether to send the cell for division or not. There are many checkpoints that cells cross during the whole cell cycle or the division process.

Complete answer:
Cell cycle refers to the cycle or simply call it as a circle which a cell needs to cover for its division. The cell cycle includes two major phases called “Interphase” and “M-Phase”. In the interphase cell prepares itself for the division and in M-Phase actual cell division occurs.
Interphase is further divided into three phases which are : G1 phase, S-Phase and G2 phase.
Checkpoints in the cell cycle are the locations from where the cell has to pass and which will decide the fate of the cell in further division. There are many checkpoints that are present, but three of them are important which are:
G1 checkpoint at G1/S transition (cell growth checkpoint)
G2 checkpoint at G2/M transition (DNA synthesis checkpoint)
The spindle checkpoint, at the transition from metaphase to anaphase. (Mitosis checkpoint)
G1 checkpoint: Here the cell has been assessed internally and the proteins are checked, if there are sufficient proteins then it will be sent to S-phase but if the proteins are insufficient then the cell goes into G0 Phase.
G2 checkpoint: Here DNA content is evaluated, if it is sufficient then it continues on to the Mitosis (M).
Spindle checkpoint: Here the completion of mitosis has been assessed.

Note:
In order to solve the question, students must have prior knowledge of the complete cell cycle, how the events take place during the division and what is the sequence of the events. This will make the understanding of checkpoints much easier. Checkpoints must be crossed by each and every cell during its division.