Explanation

In a triplet, for a particular amino acid more than one word (synonyms) can be used. This phenomenon is described by saying that the code is degenerate. A degenerate code would be one where there is one to one relation between amino acids and the codons that 44 codons out of 64 will be useless or nonsense codons. A code is degenerate because of the third base of the codon. It has been shown that the same tRNA can recognize more than one codons differing only at the third position. For example GCU, GCC and GCA all code for alanine amino acids.