Amino acids are coded for by a three nucleotide sequence on an mRNA molecule known as codon. Every amino acid is coded for by at least one codon. There are 64 universal codons, 61 codes for amino acids while 3 codes for no known amino acid and are called nonsense or stop codons. Some amino acids are coded for by more than one codons. In the genetic code dictionary, AGU codes serine, AUA codes for isoleucine, UCG codes for serine, CGU codes for arginine and UGU codes for cysteine.
