So codons consist of three nucleotides. Since there are four types of nucleotides, there are four times four times four, so 64 unique codons. And this is more than the 20 possible amino acids, which means that most amino acids are encoded by several codons. For instance, if we examine leucine, leucine contains six different codons, unique codons that essentially encode for that specific leucine amino acid. And this means all these different codons. So we have 123456 so UA ugcu cu, g CUC and cua.