A codon is a set of three DNA bases. Since a single DNA base only has 4 possible codes, in order to code for the 20 amino acids used to make proteins a set of 3 DNA bases is needed to code for them. Therefore when transcribing DNA in order to make proteins, an organism needs to read the DNA by threes.So, if I'm reading this right, there can be 64 (4x4x4) possible codons?