What I don’t understand about the Central Dogma of Molecular Biology
“DNA makes RNA makes protein makes money”
While it is true that, in general, scientists have not much time for history – or to put it another way:
Nor do I suggest that the history of science may not be profoundly interesting as history. What I am saying is that it does not often interest the scientist as science.
PB Medowar (New York Review of Books, March 28, 1968, pp 3-5)
But if there is a “historical” book (and I use the term “historical” cavalierly) that every scientist has read – and in my experience, not only every biologists but every chemist and physicist I’ve ever met – it is James Watson’s The Double Helix. And in this book, Watson writes:
Back in my rooms I lit the coal fire, knowing there was no chance that the sight of my breath would disappear before I was ready for bed. With my fingers too cold to write legibly I huddled next to the fireplace, daydreaming about how several DNA chains could fold together in a pretty and hopefully scientific way. Soon, however, I abandoned thinking at the molecular level and turned to the much easier job of reading biochemical papers on the interrelations of DNA, RNA, and protein synthesis.
Virtually all the evidence then available made me believe that DNA was the template upon which RNA chains were made. In turn, RNA chains were the likely candidates for the templates for protein synthesis. There were some fuzzy data using sea urchins, interpreted as a transformation of DNA into RNA, but I preferred to trust other experiments showing that DNA molecules, once synthesized, are very very stable. The idea of genes’ being immortal smelled right, and so on the wall above my desk I taped up a paper sheet saying DNA → RNA → protein. The arrows did not signify chemical transformations, but instead expressed the transfer of genetic information from the sequence of nucleotides in DNA molecules to the sequences of amino acids in proteins.
James Watson, The Double Helix (Chapter 21)
So, if you were to accept Watson’s recollection of things, you would need to accept that:
1) it was Watson, not Crick, who first proposed the idea of the Central Dogma (if not the term)
(at the time of writing The Double Helix, Watson may have actually believed this himself. To follow his own logic, he would have to believe it. For all we know, he may believe it today. And that Crick only came up with a fancy name to slap on top of a pre-existing concept). How does Watson feel about – in his eyes – the fact that he came up with the idea of the Central Dogma and Crick got credit for it when he (Crick) only came up with a catchy name?
2) that the concept of the Central Dogma was proposed prior to the elucidation of the Watson-Crick-Franklin-Wilkins model of the double helical structure of DNA.
3) the idea of the Central Dogma was based only on other (biochemical) evidence.