Who proposed that the genetic code for amino acids should be made up of three nucleotides?

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Question

Who proposed that the genetic code for amino acids should be made up of three nucleotides?

Accepted Answer

Correct Answer: B — George GamowStep-by-step Solution:George Gamow was a Russian-American theoretical physicist who, in 1954, proposed the triplet code hypothesis. His reasoning was purely mathematical: if the genetic code used a single nucleotide per amino acid, only 4 amino acids (4¹ = 4) could be encoded — insufficient for 20 amino acids. If two nucleotides were used per amino acid: 4² = 16 — still insufficient. If three nucleotides (triplet/codon) were used: 4³ = 64 — more than enough to encode all 20 amino acids. This mathematical logic led Gamow to propose the triplet codon system.Why the other scientists are incorrect:Franklin Stahl: Along with Matthew Meselson, demonstrated semi-conservative replication of DNA using ¹⁵N labeling experiment (Meselson-Stahl experiment, 1958). Not related to genetic code.Francis Crick: Co-discovered the double helical structure of DNA (with Watson, 1953). Later contributed to cracking the genetic code and proposed the 'wobble hypothesis' for codon-anticodon interaction. He experimentally confirmed the triplet nature of the code (with Brenner, Barnett, Watts-Tobin), but Gamow had proposed it first.Jacques Monod: Along with François Jacob, proposed the operon model and concept of mRNA (messenger RNA). Won the Nobel Prize in 1965. Not the proposer of triplet code.Extended Explanation:The genetic code was fully cracked by 1966, with contributions from Marshall Nirenberg, Heinrich Matthaei, Severo Ochoa, and Har Gobind Khorana. Key features of the genetic code: (1) It is a triplet code (codons of 3 nucleotides); (2) Degenerate/redundant (multiple codons for most amino acids); (3) Non-overlapping (each nucleotide is read only once); (4) Non-punctuated (no commas/gaps between codons); (5) Universal (same in almost all organisms, with minor exceptions); (6) Three stop codons: UAA, UAG, UGA; (7) One start codon: AUG (also codes for methionine).Key Concepts: Genetic code, triplet codon hypothesis, George Gamow, history of molecular biology, codon, 4³ = 64 combinations.

Who proposed that the genetic code for amino acids should be made up of three nucleotides?

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Who proposed that the genetic code for amino acids should be made up of three nucleotides?

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