"The origin of the genetic code"

Date:: 1968

Reference:: PP/CRI/H/4/15

Credit: "The origin of the genetic code". Source: Wellcome Collection.

2/92

$1^, ¡ti h *f)uî fyrh ^ -/ij ¿rk e' y . - • The structure of the genetic code is now fairly well known. - cc .e is a non-overlapping tri riet code. Most, but not all, o: th': 64 triplets stand for one or another of the 20 amino acids, and in most cases each amino acid is represented by more t; i : ne codon. . The best present version of the code is shown ' in Table Before starting on a detailed examination of this Table a few words of caution are necessary. The code shown there has • , , • , ^ ^ > v ce en . muy oerived from studies on Escherichia coli, tgös. it £s- VSY/ similar in such widely separated organisms- as f tobacco ^■td&nts and man. In what follows I shall assume, for convenience of exposition, that it is identical in all organisms, which is ■HMJ far from being proved. In fact it is probably untrue for rks starting codons. Again the function of ,the three presumed nonsense triplets is not known for certain... It is presumed that ÏÏAA (ochre) and J UAG (amber) are signals for chain ¿AM Isl_ <T JUyuL A^oC,.: ificj UtrH uciX, 1 ' a>Pt 7 0± UGA . ~Xt —j-s—nrrt pvph r>i~~n whrrtiwr it in nn-afte X- —ûi^haiL_Jirga4tirs«s. - n E. coli there appears to be a special mechanism for initiating the polypeptide chain, involving farmyl-methionine^ ike U-Lo\,b, /] U G ¿uA & U Gr. ' Tire-codons used by tms mec^7r^TrHftm£«-4^ been definitively$

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"The origin of the genetic code"

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