Name and explain the various stages of the cell cycle.

The cell cycle is a series of events that take place in a cell leading to the duplication of its DNA and the subsequent division of the cell to produce two daughter cells.

A cell cycle consists of two phases:

1. A non-dividing phase called the interphase, and
2. A dividing phase called the M-phase or simply mitosis.

Interphase

The two daughter cells produced from a mother cell are relatively small, with a full-sized nucleus but relatively little cytoplasm. These cells are said to be in interphase. The interphase itself has three phases —

1. First growth phase (G1) — RNA and proteins are synthesised, the volume of cytoplasm increases.
2. Synthesis phase (S) — More DNA is synthesised, the chromosomes are duplicated.
3. Second growth phase (G2) — This is a shorter growth phase in which RNA and proteins necessary for cell division continue to be synthesised.

Mitosis

Mitosis is the cell division in which one parent cell divides into identical daughter cells. Mitosis has two phases —

1. Karyokinesis — It is the division of the nucleus during cell division. It occurs in four phases:
   1. Prophase — Chromosomes have become short and thick and clearly visible inside the nucleus.
   2. Metaphase — The duplicate chromosomes arrange on the equatorial plane. Each chromosome gets attached to a spindle by its centromere.
   3. Anaphase — The centromere attaching the two chromatids divides and the two sister chromatids of each chromosome separate and are drawn apart towards opposite poles.
   4. Telophase — Spindle apparatus disappears. Chromosome become thinner and turns into a network of chromatin threads.
2. Cytokinesis — At the end of telophase, a furrow appears in the cell membrane in the middle, which deepens and finally splits the cytoplasm into two, thus producing two new cells.