Properties of the Genetic Code

Correct Answer: All of the Above

All three statements correctly describe properties of the genetic code:

• 61 sense codons + 3 stop codons: Total = 64 codons (4³). The 3 stop codons (UAA, UAG, UGA) terminate protein synthesis. The 61 remaining code for 20 amino acids.
• Triplet and degenerate: Each codon = 3 nucleotides (triplet). Since 61 codons code for only 20 amino acids, most amino acids are coded by more than one codon (degeneracy). Example: Leucine has 6 codons.
• Almost universal: The same genetic code is used by nearly all living organisms — from bacteria to humans. Minor exceptions exist (e.g., mitochondria).

Scientists (from notes)

Genetic code was deciphered by Har Gobind Khorana, Nirenberg and Holley.