what is mutation of dna
What is a mutation? A mutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke. Mutations can occur during DNA replication if errors are made and not corrected in time. 2  Mutations can also occur as the result of exposure to environmental factors such as smoking, sunlight and radiation. 3  Often cells can recognise any potentially mutation-causing damage and repair it before it becomes a fixed mutation.