• Acquired Mutations: A mutation that occurs in individual cells after fertilisation
  • A mutation in genes linked to the rate of cell division can lead to uncontrolled cell division.
  • Tumour: A mass of abnormal cells brought about by uncontrolled cell division
  • Malignant (Cancer): Tumour that invades and destroy surrounding tissues

Tumour Suppressor Gene

  • Normal: Slows cell division through production of proteins that stop cells dividing or apoptosis
  • Mutation: Gene will become inactivated so protein is not produced. Cell divides uncontrolled


  • Normal: stimulates cell division through production of proteins which results in cell division
  • Mutation: the gene can become overactive and stimulates cells to divide uncontrollably
    • A mutated proto-oncogene is called an oncogene

Types of Tumour:

  • Malignant:
    • Cancer
    • Rapid growth
    • Invasive of surrounding tissue
    • Metastasis: tumour cells can spread via blood/lymphatic systems
  • Benign
    • Non-cancerous
    • Slower growth
    • Covered in fibrous tissue that prevents invading other tissue
    • Greatly harmless, however can cause blockage and pressures and may develop into malignant

Tumour Cells

Tumour Cells differ from normal cells as:

  • Nucleus is larger and darker
  • Some cells have more than 1 nucleus
  • Irregular shapes
  • Not all proteins needed to function are produced
  • Different antigens
  • No response to growth regulating processes
  • More frequent mitosis

Causes of Tumour Growth

  • Abnormal Methylation
    • Addition of -CH3 onto DNA is used to regulate gene expression as it can determine whether a gene is transcribed and translated
    • Hypermethylation (too much methylation)
    • Hypomethylation (too little methylation)
  • Oestrogen in Breath Cancer