Types of Point Mutations

Silent Mutation – Definition

Mutated codon codes for the same amino acid.

Silent Mutation – Example

CAA (glutamine) → CAG (glutamine)

Silent Mutation – Effect

None

Missense/Conditional Mutation – Definition

Mutated codon codes for a different amino acid; replaces one amino acid with another; creates a nonsynonymous codon.

Missense/Conditional Mutation – Additional Info

Some nonsynonymous mutations are conservative.

Missense/Conditional Mutation – Example

CAA (glutamine) → CCA (proline)

Missense/Conditional Mutation – Effect

Variable

Nonsense Mutation – Definition

Mutated codon is a premature stop codon; changes a codon for an amino acid into a stop codon.

Nonsense Mutation – Consequence

Creates truncated proteins that are often nonfunctional.

Nonsense Mutation – Exception

A stop codon that changes to a coding codon lengthens the protein.

Nonsense Mutation – Example

CAA (glutamine) → UAA (stop)

Nonsense Mutation – Effect

Usually serious