Question

A human cheek cell's cycle is 24 hours. The stages within the cell cycle vary in length. G1 phase - 11 hours, G2 phase - 4 hours, S phase - 8 hours, M phase - 1 hour. Why does the cell spend 23 hours in interphase (G1-S-G2), while it spends only one hour in the M phase?

Answer 1

First, let's talk about each cell stage:
G1 phase: (The longest phase) The cell is in its "normal" state of the cell, it does its normal metabolism and function. The cell grows up during this phase until reaching a point which let the cell pass to the S phase.
S phase: S for (DNA synthesis). During this phase, the cell replicates its DNA and check if there are no errors so it can pass to the next step of its cycle.
G2 phase: is the preparation for the M phase, it syntheses all the necessary proteins that participate in the mitosis.
and finally the M phase: (M for mitosis). This is the phase where the mitosis phases occur.

The cell needs a lot of preparation and checks in G1, S and G2 to do mitosis. especially in the G1 phase which is the longest phase. It is explained by the fact that the cell should "rest and recover" after the last mitosis before getting into the second one.