The cell cycle undergoes a sequence of changes which involve a period of growth replication of DNA, Followed by cell division. This sequence of changes is called cell cycle.

` The study of the cell cycle focuses on mechanisms that regulate the timing and frequency of DNA duplication and cell division. As a biological concept, the cell cycle is defined as the period between successive divisions of a cell. During this period, the contents of the cell must be accurately replicated.

Reproduction is essential to life. Reproduction at the level of the organism ranges from the simplest fission of unicellular organisms (asexual reproduction) to the complicated process involved in the sexual reproduction of higher animals.