How many nucleotides constitute a codon?

How many nucleotides constitute a codon?

• A. 2
• B. 4
• C. 3
• D. 1

Answer: (C)

Three nucleotides make up a codon. The genetic code reads mRNA in non-overlapping triplets, starting from a start signal, so each codon specifies one amino acid or a stop. With three positions and four possible nucleotides, there are 4^3 = 64 possible codons, which is enough to cover the 20 amino acids plus stop signals and allows redundancy where multiple codons encode the same amino acid. If codons were shorter, there wouldn’t be enough combinations to encode all amino acids; if longer, there would be fewer unique codons and less efficient encoding. That’s why a codon consists of three nucleotides.

Three nucleotides make up a codon. The genetic code reads mRNA in non-overlapping triplets, starting from a start signal, so each codon specifies one amino acid or a stop. With three positions and four possible nucleotides, there are 4^3 = 64 possible codons, which is enough to cover the 20 amino acids plus stop signals and allows redundancy where multiple codons encode the same amino acid. If codons were shorter, there wouldn’t be enough combinations to encode all amino acids; if longer, there would be fewer unique codons and less efficient encoding. That’s why a codon consists of three nucleotides.