Explain various phases of cell cycle in detail.

Explanation

A typical eukaryotic cell is illustrated by human cells in culture
The duration of cell cycle can vary from organism to organism and also from cell type to cell type.
A cell cycle gets completed at every 24 hours in human beings.
Yeast can progress through the cell cycle in about 90 minutes.
The cell cycle is divided into two basic phases :
(1) Interphase
(2) M - Phase (Mitosis phase)
The M - Phase represents the phase when the actual cell division or mitosis occurs.
The interphase represents the phase between two successive M - phases.

It is significant to note that in the 24 hours average duration of cell cycle of a human cell, cell division lasts for only about an hour.
The interphase lasts for more than 95% of the duration of cell cycle.
The M - Phase starts with the nuclear division, corresponding to the separation of daughter chromosomes (Karyokinesis) and usually ends with division of cytoplasm (Cytokinesis).
The interphase, though called the resting phase, is the time during which the cell is preparing for division by undergoing both cell growth and DNA replication in an orderly manner.

The interphase is divided into three further phases :
(a) `G_1` phase (Gap 1)
(b) S phase (Synthesis)
(c) `G_2` phase (Gap 2)