A mutation is a change in a gene or chromosome.

Mutations occur continuously and are often random changes in the genetic material that can be inherited. There is extensive genetic variation within a population caused by mutations.

Causes of mutation

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Mutation occurs continuously and can be spontaneous. It can also happen:

  • when cells are copying themselves during mitosis (cell division)
  • if a person comes into contact with environmental factors such ionising radiation
  • because of chemical mutagens - such as tar from cigarette smoke

Mutations may change the activity of a protein, in a coding part of the DNA, or might change how the genes are expressed if the change is in a non-coding section of DNA. These might result in phenotype changes or they might appear hidden, and be unnoticed. Alternatively, they might result in a serious consequence, such as genetic disease such as cystic fibrosis.