What does degeneracy of the genetic code mean?

• A. Some amino acids are coded by more than one codon
• B. Each codon codes for multiple amino acids
• C. Codons are always unique per amino acid
• D. Only stop codons show degeneracy

Answer: (A)

Degeneracy means there is redundancy in how the genetic code maps codons to amino acids: the same amino acid can be encoded by several different codons. This is why some amino acids, like leucine, serine, and arginine, each have multiple codons. Because of this redundancy, many changes in the third base of a codon don’t change which amino acid is added, leading to silent mutations. It’s not that a single codon codes for multiple amino acids, and it’s not true that only stop signals show degeneracy; instead, the code is organized so that multiple codons can specify the same amino acid, providing built-in tolerance to some mutations.