How many nucleotides constitute a codon in RNA?

How many nucleotides constitute a codon in RNA?

• A. 3
• B. 2
• C. 4
• D. 5

Answer: (A)

In RNA, a codon is read as a group of three nucleotides. With four bases (A, U, C, G), three positions yield 4^3 = 64 possible codons, which is enough to code for all 20 amino acids plus stop signals, while allowing redundancy so multiple codons can encode the same amino acid. If you used only two nucleotides, there would be 4^2 = 16 possible codons—far too few to map onto all amino acids and signals. If you used four or five nucleotides per codon, you’d generate 256 or 1024 possibilities, far more than needed and would complicate the translation system. Three nucleotides per codon is the right balance.

In RNA, a codon is read as a group of three nucleotides. With four bases (A, U, C, G), three positions yield 4^3 = 64 possible codons, which is enough to code for all 20 amino acids plus stop signals, while allowing redundancy so multiple codons can encode the same amino acid. If you used only two nucleotides, there would be 4^2 = 16 possible codons—far too few to map onto all amino acids and signals. If you used four or five nucleotides per codon, you’d generate 256 or 1024 possibilities, far more than needed and would complicate the translation system. Three nucleotides per codon is the right balance.