Jim and I hit it off immediately, partly because our interests were astonishingly similar and partly, I suspect, because a certain youthful arrogance, a ruthlessness, an impatience with sloppy thinking can naturally to both of us. Francis Crick More Quotes by Francis Crick More Quotes From Francis Crick 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 simplicity class thinking 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 indirect evidence method If poly A is added to poly U, to form a double or triple helix, the combination is inactive. Francis Crick double-standard combination form Finally one should add that in spite of the great complexity of protein synthesis and in spite of the considerable technical difficulties in synthesizing polynucleotides with defined sequences it is not unreasonable to hope that all these points will be clarified in the near future, and that the genetic code will be completely established on a sound experimental basis within a few years. Francis Crick dna sound years Protein synthesis is a central problem for the whole of biology, and that it is in all probability closely related to gene action. Francis Crick synthesis action science 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 members messages two 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 mutation finals ideas If, for example, all the codons are triplets, then in addition to the correct reading of the message, there are two incorrect readings which we shall obtain if we do not start the grouping into sets of three at the right place. Francis Crick reading messages two It would appear that the number of nonsense triplets is rather low, since we only occasionally come across them. However this conclusion is less secure than our other deductions about the general nature of the genetic code. Francis Crick nonsense lows numbers Unfortunately it makes the unambiguous determination of triplets by these methods much more difficult than would be the case if there were only one triplet for each amino acid. Francis Crick acid determination would-be 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. Francis Crick mutation acid agreement The 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 Crick acid minorities may 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 data views order It now seems certain that the amino acid sequence of any protein is determined by the sequence of bases in some region of a particular nucleic acid molecule. Francis Crick acid molecules determined 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. Francis Crick logical foundation doe We've discovered the secret of life. Francis Crick the-secret-of discovered secret life
