Hinted by Philip Johnsson on the ARN Weekly Wedge Update I read the article by Barry Commoner on "Unraveling the DNA myth" http://www.mindfully.org/GE/GE4/DNA-Myth-CommonerFeb02.htm .
Not being in a profession related to molecular biology I would like a few thoughts cleared out by someone who is.
Commoner first argues that the central dogma of molecular biology is false. This central dogma includes, as far as I understand, the fact that DNA is the sole repository of information related to production of proteins and that given the DNA structure all proteins in a living organism can be reproduced accurately (not only regarding amino acid sequence but also regarding proper folding etc.). According to Commoner the central dogma implies that there would be a one-to-one relationship between genes and proteins.
This was also the underlying idea behind the Human Genome Project, which intended to catalogue all human genes in order to specify what makes a human being a human being (in terms of heredity). Commoner notes the fallacy in this reasoning as the results show only 30,000 human genes, of which 99 % are similar to the ones of a mouse. The estimated number of human proteins are at least 100,000.
Commoner mentions "alternative splicing", which is a way for one single gene to produce many different proteins, by spliceosomes reorganizing the RNA structure.
Finally, Commoner makes the conclusion that "genetic information arises not from DNA alone but through its essential collaboration with protein enzymes".
What I wonder now is if this last statement really needs to be correct? There might not be a one-to-one relation between genes and proteins, but the information can be in the DNA anyway.
Supposing there is a need for spliceosomes to create all functional proteins in an organism. But these spliceosomes are also created some way, possibly through some DNA gene.
If you assume 30,000 genes in human DNA, a small percentage of these might be used for producing spliceosomes. According to Commoner one single gene might generate up to 38,016 variant protein molecules though alternative splicing.
If the spliceosomes are responsible for turning the 30,000 genes into 100,000 proteins, and the spliceosomes themselves are created through a few of these genes, isn't it still relevant to say that all genetic information arises from DNA information? It is just one level of indirection, genes doesn't only create proteins directly (via RNA) but also by creating spliceosomes that modifies the RNA order and thus produce new proteins?
Thus, the "information content" in human DNA in terms of proteins-creation capability is not 30,000 but in this case the appropriate 100,000. In fact the theoretical information content (not caring about which combinations are functional) can be enormous!
It's a bit like computer systems. On a hard-disk (DNA) you have both data, and programs able to manipulate data. But all necessary information is nevertheless stored on the hard-disk.