The level of cyclins in a cell increases during the M phase of the cell cycle what might happen to a cell if no cyclins were present during the M phase

If no cyclins were present during the M phase, then the cell cannot progress through the cell cycle.

In conclusion, if no cyclins were present during the M phase, then the cell cannot progress through the cell cycle.

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If cyclins were not present in phase M of the cell cycle, cell division would not be possible, since that phase could not be initiated.

Explanation:

Cyclins are regulatory proteins within the cell cycle and, specifically in phase M, are responsible for causing the nucleus to lose its nuclear envelope and heterochromatin condenses to form chromosomes.

During the cell division phase (phase M) the M-cyclins are the initiators of the events that initiate this process. To that end, they must bind to inactive enzymes, Cyclin-dependent kinases (CDKs), and activate them.

M-cyclins remain inactive in other phases of the cell cycle, inhibited by inhibitory protein factors that keep them phosphorylated. Phosphatases enzymes eliminate phosphorylation of cyclines, increasing their levels within the cell.  Once active, kinases activate CDKs, and phase M begins.

If M cyclins were not present, or it was not possible to dephosphorylate them, the M phase of the cell cycle could not be initiated.

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