Mutations

• 1.Single gene mutations involve the alteration of a DNA nucleotide sequence

  2. As a result of the substitution, insertion or deletion of nucleotides.

  3. A substitution mutation is where one DNA nucleotide is swapped for a different one.

  4. Substitution can result in missense, nonsense or splice site mutations.

  5. Missense mutations result in one amino acid being changed for another.

  6. This may result in a non-functional protein ( may no longer function because the shape of the protein has been altered) or have little effect on the protein depending on which amino acid is affected.
• 7. Nonsense mutations result in a premature stop codon being produced which results in a shorter protein.

  8. Splice-site mutations result in some introns being retained and/or some exons not being included in the mature transcript.

  9. Insertion mutations involve an extra DNA nucleotide being inserted into the sequence.

  10. Deletion mutations involve a DNA nucleotide being deleted from the sequence.

  11. Frame-shift mutations cause all of the codons and all of the amino acids after the mutation to be changed.

  12. This has a major effect on the structure of the protein produced.