In eukaryotic cells, cell proliferation results from a tightly controlled process known as the cell cycle

• The cell cycle is a repeating sequence of events that occurs between one cell division and the next
  

• This cycle is divided into two main stages – interphase (including G1, S and G2) and the M phase (mitosis and cytokinesis)

Interphase

Interphase is the metabolically active period between cell divisions and is a continuum of three distinct phases

• G1 – First intermediate gap stage in which the cell grows and prepares for DNA replication
  

• S – Synthesis stage in which DNA is replicated
  

• G2 – Second intermediate gap stage in which the cell finishes growing and prepares for cell division
  

M phase

The M phase consists of two distinct periods in which the cell and contents divide to create two genetically identical daughter cells

• Mitosis – Nuclear division, whereby DNA (as condensed chromosomes) is separated into two identical nuclei
  

• Cytokinesis – Cytoplasmic division, whereby cellular contents are segregated and the cell splits into two
  

Some cells may leave the cell cycle and enter into a non-dividing quiescent state called G0 (i.e. resting stage)

• Cells in this state will perform their differentiated function but do not divide further (e.g. neurons)