Reprints 51-55

Date:
1963-1964
Reference:
PP/CRI/M/1/2
Catalogue details

Licence: In copyright

Credit: Reprints 51-55. Source: Wellcome Collection.

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    B. Ambiguous Codons C. Unlikely Codes D. Woese 's Code . VE. General Observations A. The Nature of the Code B. Future Developments' C. On the Place of Theorj Addendum References I. Introduction A. The Nature of the Problem The Sequence Hypothesis states that the amino acid seq;uen^of a protein is determined by the sequence of nucleotides inMSO^|pS^cuíar piece of nucleic acid. The evidence in favor of this is nov^o^lwnslder- able, and will not be reviewed here. It is not imreasoiuSle^^tóeHbat this relationship may be a simple one and that the s e quen%è~' trfjuie if our bases in the nucleic acid can be thought of as a simple co3eÍfó'i'-t¿e«mino acid sequence. ; . This problem—the exact sequence of bases that detemínea.pach' oí the twenty amino acids found in proteins—is known^as^the^ícoding problem. Recently there have been dramatic developmentalÄis-field and it now seems possible that the code will be found within a> compara tively short time. This review deals critically with the recer't progress and discusses the general nature of the genetic code astweS^^^inpse it today. B. The Mechanism of Protein Synthesis The actual mechanism of protein synthesis will not'be '.tÇonâderêd here in any detail. We assume that the main site ot vsynthiîsis is ihe ribosomes; that the genetic message is conveyed there iby Ssëjfwçial species of RNA known as messenger RNA (see Lipmanñ'sarti cíe in this volume), which is usually made by copying one of th'ejii&ar'^sJoî4he double helix of DNA (see Hurwitz and August's article in ihis volume) ; and that the amino acids are conveyed to the ribosomes ijy ? A§£®.cîal family of RNA molecules known as ''soluble RNA or'¿transi'e^NA'' (here called sRNA), which act as adaptors and carry each'a: 1 ™?- 0 acid to its proper site. It is known that the sRNA molecules are*Sp aE( ^ that there is at least one type for each amino acid. Each amipò^acid-is joined onto its own sRNA by a special protein—the actiyátíng °nzyme— in a way that is fairly well understood (Hoagland, ]