Point mutations - when a single nitrogen base is deleted, inserted or substituted.
  1.  Non-sense mutation - when a stop codon occurs because of a substitution.
  2 . Missense mutation - when a different amino acid is coded for because of a substitution.
  3.  Frameshift - when many amino acids coded for are different because of an  insertion or deletion.

The following example shows how these 3 kinds of mutations work.  Fill out the RNA and protein for each and compare the mutations to the original.  The mutation is in bold.
 

Original DNA   T A C  G C G  T G C  A C G  A T G  C A G  T A G  T A C

  RNA

  Protein
 

Mutation 1 DNA   T A C  G C G  T G C  A C G  A T C  C A G  T A G  T A C

  RNA

  Protein
 

Mutation 2 DNA   T A C  G C G  T G C  T C G  A T G  C A G  T A G  T A C

  RNA

  Protein
 

Mutation 3 DNA   T A C  G C G  C T G  C A C  G A T  G C A  G T A  G T A  C

  RNA

  Protein