55. Mutations: Base changes Very harmful : - deletion / insertion of one base - deletion / insertion of two bases Especially in the beginning of a ORF/gene If at the end of a gene, the ‘shorter’ (or the to the-C-terminal-end-aberrant) protein can still be active Less harmful : - base substitution (another amino acid; but can also become a stop codon) - deletion / insertion of three bases (loss of an extra amino acid)