Point mutation

 A point mutation refers to a substitution of a single base nucleotide in a sequence of DNA or RNA. The effects of this may be silent (in which after the substitution, the sequence still codes for the same amino acid due to the genetic code being degenerate), nonsense (the substitution leads to the sequence coding for a stop codon) or missense (the substitution leads to the sequence coding for a different amino acid which may have similar or different properties and alter the functionality of the polypeptide).