The genetic code translates mRNA nucleotide sequences to amino acid sequences. Genetic information is coded using this process with groups of three codons along the mRNA which are commonly known as codons.[7] The set of three nucleotides almost always produce the same polypeptide with are a few exceptions like UGA which typically serves as the stop codon but can also encode tryptophan in mammalian mitochondria.[1] Most amino acids are specified by multiple codons demonstrating that the genetic code is degenerate–different codons result in the same amino acid.[7] Codons that code for the same amino acid are termed synonyms.