One codon makes up an amino acid. A codon is defined as a sequence of three nucleotides. Taken together, this sequence of nucleotides forms a single unit of genetic code found within a DNA or RNA molecule.
The codon determines the manner in which the insertion of an amino acid in a polypeptide chain occurs during protein synthesis. A codon is also involved in signaling when protein synthesis is to stop. All of the proteins that are found within the human body are made up of a total of 64 codons. Twenty different amino acids make up all of the proteins found in a human body.