 Degeneracy of the genetic code

Degeneracy of the genetic code means that distinct codons can specify the same amino acid. For example, UUU and UUC both specify phenylalanine in the standard genetic code.^[ref] In the original AUG GCU UUC UGA example, changing UUC to UUU preserves the predicted amino acid order. This illustrates redundancy of assignment, not equality of every possible effect on gene expression.

Degeneracy of the genetic code differs from ambiguity: multiple inputs share one output, whereas an ambiguous assignment would give a single codon more than one meaning in the same specified decoding context. The standard genetic code table has one listed assignment per triplet. Alternative genetic codes, including those used in some mitochondria, and engineered decoding contexts must be specified separately; the standard table is not a universal statement about all organelles or synthetic systems.