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Codon is a sequence of nucleotides (generally three) in DNA or RNA that corresponds to the specific amino acid.

Codon is a sequence of nucleotides (generally three) in DNA or RNA that corresponds to the specific amino acid.

Generally, the genetic code is a triplet, not a doublet or quartet. There are total of four nucleotides. So the number of different possible codons using four nucleotides is (4)ⁿ , where n is the number of nucleotides in the code.

For two-letter code: (4)²= 16

For three-letter code: (4)³ = 64

For four-letter code:(4)⁴= 256

There are 20 amino acids. Therefore we can say that two-letter code would not provide enough codons.

A three-letter code provides enough codes for all the amino acids and also provides the necessary stop codon.

A four-letter code provides many more codes than would be needed.