Mutations

• Mutations


  Changes to the genetic code
• Mutations occur


  1. Spontaneously

  2. Due to exposure to substances or radiation
• Genetic variant


  A different form of the gene
• Mutations change the DNA base sequence


  Can lead to changes in the protein it codes for
• Effects of mutations on proteins

  • Little or no effect
  • Change protein shape and function
• Effects of mutations on proteins

  • Enzyme active site shape changed, substrate can no longer bind
  • Structural proteins like collagen lose strength
• Non-coding DNA


  Can have mutations that alter gene expression
• Types of mutations


  • Insertions
  • Deletions
  • Substitutions
• Insertions


  1. New base inserted into DNA sequence

  2. Changes how groups of 3 bases are read

  3. Can change more than one amino acid
• Insertion example


  • TATAG TCT T -> TATAGGTCTT
• Deletions


  1. Random base deleted from DNA sequence

  2. Changes how sequence is read

  3. Have knock-on effects
• Substitutions


  Random base in DNA sequence changed to different base
• Substitution example


  • AACTCTT -> AGACTT