Final answer:
The genetic code is redundant, which means that one amino acid can be specified by multiple codons. This helps reduce the impact of mutations and allows for some flexibility in protein synthesis.
Step-by-step explanation:
The genetic code is redundant, meaning that a given amino acid can be encoded by more than one nucleotide triplet. This redundancy is called degeneracy and it helps reduce the negative impact of random mutations. Codons that specify the same amino acid typically only differ by one nucleotide, usually the third one. For example, ACU, ACC, ACA, and ACG all code for the amino acid threonine. Additionally, amino acids with chemically similar side chains are encoded by similar codons. For example, UGU and UGC code for the amino acid cysteine, while AGU and AGC code for the amino acid serine. This ensures that a single-nucleotide substitution mutation might specify either the same amino acid or a similar amino acid, preventing the protein from being rendered completely nonfunctional.