Codons in the genetic code specify how many amino acids?

Codons in the genetic code specify how many amino acids?

• A. 64
• B. 61
• C. 20
• D. 4

Answer: (C)

Codons are three-nucleotide units that specify which amino acid gets added during protein synthesis. With four possible bases, there are 4 × 4 × 4 = 64 possible codons. Three of these act as stop signals, so they don’t code for an amino acid. That leaves 61 codons that code for amino acids, but there are only twenty different amino acids used to build proteins. Multiple codons can encode the same amino acid, which is why the code is redundant. So, the number of amino acids specified by codons is twenty.

Codons are three-nucleotide units that specify which amino acid gets added during protein synthesis. With four possible bases, there are 4 × 4 × 4 = 64 possible codons. Three of these act as stop signals, so they don’t code for an amino acid. That leaves 61 codons that code for amino acids, but there are only twenty different amino acids used to build proteins. Multiple codons can encode the same amino acid, which is why the code is redundant. So, the number of amino acids specified by codons is twenty.