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.
A comparison between the triplets tentatively deduced by these methods with the changes in amino acid sequence produced by mutation shows a fair measure of agreement.
We are sometimes asked what the result would be if we put four +’s in one gene. To answer this my colleagues have recently put together not merely four but six +’s.
For simplicity one can think of the + class as having one extra base at some point or other in the genetic message and the – class as having one too few.
A knowledge of the true age of the Earth and of the fossil record makes it impossible for any balanced intellect to believe in the literal truth of every part of the Bible in the way that fundamentalists do.
A final proof of our ideas can only be obtained by detailed studies on the alterations produced in the amino acid sequence of a protein by mutations of the type discussed here.
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.
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.
