Which statement best describes the genetic code's triplet nature?

Which statement best describes the genetic code's triplet nature?

• A. It uses triplet codons to specify amino acids.
• B. It uses doublets to specify amino acids.
• C. It uses quadruplets to specify amino acids.
• D. It uses single nucleotides to specify amino acids.

Answer: (A)

Three-nucleotide units called codons carry the instruction for which amino acid to add during translation, so the genetic code is read in triplets. Because there are four nucleotides, using three at a time gives 4^3 = 64 possible codons, which is enough to specify the 20 amino acids plus stop signals. That’s why this triplet system is the simplest, most functional way to encode all the amino acids. If you tried using doublets, you’d only have 16 possibilities—far too few to uniquely specify all amino acids and stops. Single nucleotides offer just 4 possibilities, and while quadruplets would give many more, the cellular machinery is built to read in threes, making a triplet code the practical and workable solution.

Three-nucleotide units called codons carry the instruction for which amino acid to add during translation, so the genetic code is read in triplets. Because there are four nucleotides, using three at a time gives 4^3 = 64 possible codons, which is enough to specify the 20 amino acids plus stop signals. That’s why this triplet system is the simplest, most functional way to encode all the amino acids. If you tried using doublets, you’d only have 16 possibilities—far too few to uniquely specify all amino acids and stops. Single nucleotides offer just 4 possibilities, and while quadruplets would give many more, the cellular machinery is built to read in threes, making a triplet code the practical and workable solution.