mutations

insertion mutation

frameshift mutation - can change the amino acid sequence, affecting protein structure. this mutation changes the amino acid that would have been coded for the original base triplet (eg. ACC → ACG)

deletion mutation

base is randomly deleted from the DNA sequence
frameshift mutation - can change structure of protein

silent mutations

mutation does not alter amino acid sequence of polypeptide

missense mutations

alters a single amino acid in the polypeptide chain (eg. sickle cell anaemia)

nonsense mutations

creates a premature stop codon - polypeptide chain will be incomplete, affecting protein structure

beneficial mutations

altered characteristic which causes beneficial affects eg. melanin production providing protection from UV radiation

harmful mutations

altered characteristic which causes harmful effects for the organisms (eg. cystic fibrosis, CFTR protein and deletion mutations)

neutral mutations

offers no selective advantage/disadvantage (eg - TAS2R38 taster ability. increased perception of bitterness)