Mutation

• Mutations are random changes in the nucleotide sequence of amino gene that affects the phenotype of organism
• Gene mutations are a change in the sequence if bases in a gene, causes altered codon in mRNA sequence that may alter amino acid sequence of polypeptide chain
• Types of gene mutations:

  • Substitution
  • Insertion/Addition
  • Deletion
• Base substitution:

  • only one nucleotide is replaced by another
  • silent mutation - codon still codes for same amino acid
  • nonsense mutation - stop codon is introduced
  • missense mutation - codon codes for different amino acid
• Base insertion & Base deletion:

  • result in frames frameshift mutations
  • deleting or inserting one nucleotide of DNA will change which bases are read together, all subsequent codon and amino acids are affected