14.4 Gene Mutation

Mutations

Nonsense Mutation- This is where the original base sequence is changed so that a stop codon is formed, resulting in the premature ending of polypeptide production, causing the protein to be incomplete and not function properly.

Mis-sense Mutation- The base changed results in a different amino acid being formed. This could therefore change the tertiary structure of the protein; if this is an enzyme then it will not function properly as the active site will change shape.

Silent Mutation- Because the triplet code is degenerate, a change in one base may lead to there being no change in the amino acid produced.

The two types of mutation are deletion and Substitution.

With deletion, the closer to the start the base that’s deleted is, the more effect there will be.

Some chemicals can…