Describe different point mutations and how severe are they likely to be

Insertion - one nucleotide is inserted into already existing sequence. As amino acids are coded by 3 consistent nucleotides insertion changes the reading frame. Therefore, it is likely to have severe consequences as all amino acids post mutation point will be changedSubstitution - one nucleotide in existing sequences is substituted with different one. This mutation doesn't change the reading frame, it only changes one nucleotide therefore less severe consequences can be expected. Some of those mutations can be 'silent' as the same amino acid is still produced. The exception is nonsense mutation which changes given amino acid into STOP codon and stops transcription prematurely. Deletion - one nucleotide is deleted from existing sequence. As in insertions the reading frame shifts which is likely to have severe consequences