What are gene mutations?

A mutation is any change to the base sequence of DNA.

The different types of mutations that can occur include:

Subsitution - this is where one base is swapped for another

Deletion - one or more bases are removed from the sequence

Insertion - one oe more bases are added to the sequence

Duplication - one or more bases are repeated

Inversion - a sequence of bases is reversed, for example if a sequence was ATAGC, then an inversion mutation would cause it to become CGATA

 

Mutations don't always necessarily cause changes to the primary structure as the amino acid code is degenerate (more than one base sequence codes for the same amino acid)

For example TAT and TAC both code for the amino acid Tyrosine, so if the T was substituted for a C it wouldn't make a difference to the primary structure. 

 

However some mutations have a large effect on the base sequence. As the amino acid code is read in triplets, if a base is deleted or inserted it causes a frame shift, it changes the way the rest of the sequence is read.