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. Francis Crick answeraskcolleague Change image and share on social
How is the base sequence, divided into codons? There is nothing in the backbone of the nucleic acid, which is perfectly regular, to show us how to group the bases into codons. Francis Crick acidbackbonebase Change image and share on social
It has yet to be shown by direct biochemical methods, as opposed to the indirect genetic evidence mentioned earlier, that the code is indeed a triplet code. Francis Crick biochemicalcodedirect Change image and share on social
Attempts have been made from a study of the changes produced by mutation to obtain the relative order of the bases within various triplets, but my own view is that these are premature until there is more extensive and more reliable data on the composition of the triplets. Francis Crick attemptbasiscomposition share on social
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. Francis Crick acidaminobalance share on social
Do codons overlap? In other words, as we read along the genetic message do we find a base which is a member of two or more codons? It now seems fairly certain that codons do not overlap. Francis Crick basecodonfairly Change image and share on social
It now seems very likely that many of the 64 triplets, possibly most of them, may code one amino acid or another, and that in general several distinct triplets may code one amino acid. Francis Crick acidaminocode Change image and share on social
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. Francis Crick baseclassextra Change image and share on social
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. Francis Crick acidalterationamino Change image and share on social
