The code of life / [Ernest Borek].

  • Ernest Borek
Date:
1965
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The code of life / [Ernest Borek]. Source: Wellcome Collection.

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    than that of the code. These supernumerary RNAs for the same amino acid are real entities isolated from biological material, whereas the artificial messenger RNA's are man-made and function in a highly artificial reconstruction of a cell's protein- making apparatus. It is obvious that much effort and some incisive thinking are needed before a cogent reason for this apparent relaxation of the cell's stringent specificity becomes apparent. On the other hand, there are telling lines of evidence attesting the over-all validity of the Nirenberg Code. The reader will recall that we know the defect in sickle-cell hemoglobin: a glutamic acid was replaced, due to a genetic blunder, by the amino acid valine. What had occurred in the RNA to bring about the unfortunate shift: glutamic acid —> valine ? The code word in RNA deduced for glutamic acid is AUG; for valine it is UUG. I should emphasize again that the sequence of the bases is not known; nor are we certain whether the code word contains but three bases or perhaps some multiple of three. Nevertheless, it is apparent that the minimal change of the substitution of a U for an A in RNA will transform AUG —> UUG and, consequently, Glutamic Acid —> Valine The original mutation which must have occurred in the DNA of some ancestor of the millions who today suffer from sickle-cell anemia can be symbolized the following way: DNA : TAC MutatioP > AAC 1 1 Messenger RNA : AUG UUG I I. Glutamic Valine Acid (The TAC and AAC are the sequences in DNA complementary to the AUG and UUG of the messenger RNA.)