Mitosis is the process by which eukaryotic somatic (body) cells divides to produce two genetically identical daughter cells

There are four main processes in eukaryotic organisms which may involve mitosis:

  • Growth:  Multicellular organisms increase their size by  increasing their number of cells through mitosis
  • Asexual reproduction:  Certain eukaryotic organisms may reproduce asexually by mitosis (e.g. vegetative reproduction)
  • Tissue Repair:  Damaged tissue can recover by replacing dead or damaged cells
  • Embryonic development:  A fertilised egg (zygote) will undergo mitosis and differentiation in order to develop into an embryo

Overview of Mitosis


  • DNA supercoils, causing chromosomes to condense and become visible under a light microscope
  • As DNA was replicated during interphase, the chromosomes are each comprised of two genetically identical sister chromatids joined at a centromere
  • The centrosomes move to opposite poles of the cell and spindle fibres begin to form between them (in animals, each centrosome contains 2 centrioles)
  • The nuclear membrane is broken down and disappears


  • Spindle fibres from the two centrosomes attach to the centromere of each chromosome
  • Contraction of the microtubule spindle fibres cause the chromosomes to line up separately along the centre of the cell (equatorial plane)


  • Continued contraction of the spindle fibres cause the two sister chromatids to separate and move to the opposite poles of the cell
  • Once the two chromatids in a single chromosome separate, each constitutes a chromosome in its own right


  • Once the two sets of identical chromosomes arrive at the poles, the spindle fibres dissolve and a new nuclear membrane reforms around each set of chromosomes
  • The chromosomes decondense and are no longer visible under a light microscope
  • The division of the cell into two daughter cells (cytokinesis) occurs concurrently with telophase