Mitosis & the Cell Cycle (OCR Gateway GCSE Biology: Combined Science)

Revision Note

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The Cell Cycle

  • The cell cycle can be thought of as the life cycle of a cell
  • It is the series of growth and development steps a cell undergoes
    • From its formation to the point it divides to make new cells
  • The cells in your body need to be able to divide to help your body grow and repair itself
    • Cells grow and divide over and over again
    • For this to happen the DNA has to be copied
  • All body cells (except gametes) are produced by mitosis which happens as part of the cell cycle

There are 3 parts of the cell cycle

  • Interphase - consists of phases of cell growth and synthesis of new DNA
    • Just before mitosis, the DNA in the nucleus copies itself exactly (forming duplicate chromosomes)
  • Mitosis - Chromosomes line up along the centre of the cell and are pulled apart
  • Cytokinesis - The cell cytoplasm and membrane divides to produce two daughter cells
    • Each new cell has a copy of each of the chromosomes

The 3 stages of the cell cycle, downloadable IGCSE & GCSE Biology revision notes

The three stages of the cell cycle


  • The process of mitosis is itself made up of a series of stages that begin after interphase has occurred
    • DNA was copied during interphase to produce duplicate chromosomes 
  • During mitosis, the sets of duplicated chromosomes line-up in the centre of the cell
  • Cell fibres attach to the duplicated chromosomes and pull them apart
  • One chromosome arm (chromatid) from each set is pulled to each end of the cell
  • A new nucleus forms around each group of chromosomes
  • After this, the cytoplasm and cell membranes divide in a process known as cytokinesis. This results in the formation of two genetically identical daughter cells

Mitosis, IGCSE & GCSE Biology revision notes

Diagram showing the process of cell division by mitosis

Exam Tip

You do need to appreciate the three overall stages of the cell cycle:

  • Growth phase (including chromosome doubling)
  • Mitosis
  • Cytokinesis (division of cytoplasm and the cell membrane)

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