Gene Mutations

What is a gene mutation?

A change in the base sequence of a chromosome

What is a mutagenic agent?

Outside factors which increase the rate of mutations

What are the two types of gene mutation?

• Base deletion

• Base substitution

What is a base deletion?

When a base is removed from the DNA sequence

What is a base substitution?

When a base is swapped out for another in the DNA sequence

Why does a base deletion cause a large change in the primary structure of a polypeptide?

It causes a frameshift, changing all the triplets

What are the two reasons why a mutation may not affect the primary structure of a protein?

• The mutation may result in a triplet that codes for the same amino acid

• The mutation could occur in a non-coding region of DNA

Why could a change to the primary structure lead to a non-functional protein?

Affects the hydrogen bonds, ionic bonds and disulphide bridges in the tertiary structure