The balance of evidence both from the cell-free system and from the study of mutation, suggests that this does not occur at random, and that triplets coding the same amino acid may well be rather similar.
It seems likely that most if not all the genetic information in any organism is carried by nucleic acid – usually by DNA, although certain small viruses use RNA as their genetic material.
Exploratory research is really like working in a fog. You don’t know where you’re going. You’re just groping. Then people learn about it afterwards and think how straightforward it was.
Again the message to experimentalists is: Be sensible but don’t be impressed too much by negative arguments. If at all possible, try it and see what turns up. Theorists almost always dislike this sort of approach.
If 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.
Almost all aspects of life are engineered at the molecular level, and without understanding molecules we can only have a very sketchy understanding of life itself.
Trying to determine the structure of a protein by UV spectroscopy was like trying to determine the structure of a piano by listening to the sound it made while being dropped down a flight of stairs.
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.
