It is one of the more striking generalizations of biochemistry - which surprisingly is hardly ever mentioned in the biochemical textbooks - that the twenty amino acids and the four bases, are, with minor reservations, the same throughout Nature.
Francis CrickIf the code does indeed have some logical foundation then it is legitimate to consider all the evidence, both good and bad, in any attempt to deduce it.
Francis CrickThe meaning of this observation is unclear, but it raises the unfortunate possibility of ambiguous triplets; that is, triplets which may code more than one amino acid. However one would certainly expect such triplets to be in a minority.
Francis CrickWhat could be more foolish than to base one's entire view of life on ideas that, however plausible at the time, now appear to be quite erroneous? And what would be more important than to find our true place in the universe by removing one by one these unfortunate vestiges of earlier beliefs?
Francis CrickMoreover the incorporation requires the same components needed for protein synthesis, and is inhibited by the same inhibitors. Thus the system is most unlikely to be a complete artefact and is very probably closely related to genuine protein synthesis.
Francis CrickThe major credit I think Jim and I deserve ... is for selecting the right problem and sticking to it. It's true that by blundering about we stumbled on gold, but the fact remains that we were looking for gold. Both of us had decided, quite independently of each other, that the central problem in molecular biology was the chemical structure of the gene. ... We could not see what the answer was, but we considered it so important that we were determined to think about it long and hard, from any relevant point of view.
Francis Crick