The Cell Cycle

The cell cycle describes the lifespan of a eukaryotic somatic cell, which is any body cell except sex cells. It outlines the sequence of cell growth and division.

A cell spends most of its life in interphase, which has three sub-phases: G1, S, and G2. Interphase is followed by the M phase, which is cell division. Together, these four phases constitute the entire cell cycle.

The G1 phase, also known as growth one or gap phase one, is when a cell grows and performs its specific functions. Some cells, like muscle and nerve cells, exit the cell cycle after G1 as they do not divide again.

The cell enters the S phase (synthesis) when it needs to divide. During this phase, a copy of the DNA is made through replication.

After DNA replication, the cell enters the G2 phase, also known as growth two or gap phase two. In G2, the cell undergoes further preparations for cell division.

Once interphase is complete, the cell is ready for the M phase, which involves cell division. The M phase has two main events: mitosis (division of the cell's nucleus) and cytokinesis (division of the cytoplasm). At the end of the M phase, two daughter cells, identical to each other and the original cell, are formed.

To review, the cell cycle illustrates the life of a cell, comprising four phases: three in interphase (G1 for growth and function, S for DNA replication, G2 for further preparation) and one for cell division (M phase, including mitosis and cytokinesis).