1.4.15 Explain how errors in DNA replication can give rise to mutations and explain how cystic fibrosis results from one of a number of possible gene mutations.

Mutation: during DNA replication/ transcription/ translation (any stage when the genetic code is copied) a mistake can be made in the new base sequence formed. This changes the base sequence on the DNA, which can give rise to a change in amino acid sequence in the protein, in turn, this changes the protein structure, affecting the formation of the correct protein.

Mutations that occur during DNA replication can have the greatest effect because they are passed to new cells: in body cells they may lead to cancer, in gametes they can be passed to offspring and lead to genetic disorders such as cystic fibrosis.