Central Dogma

The central dogma of molecular biology seemed to confirm the Weismann barrier idea. But it doesn’t. The dogma was misinterpreted to mean that information could not pass from the organism and environment to the genome. To quote The Selfish Gene, genes are “sealed off from the outside world.” This is simply incorrect.

“The mechanisms of transposable elements illustrate one of the important breaks with the central dogma of molecular biology. Retrotransposons are DNA sequences that are first copied as RNA sequences, which are then inserted back into a different part of the genome using reverse transcriptase. DNA transposons may use a cut-and-paste mechanism that does not require an RNA intermediate. As Beurton et al.(2008) comment, ‘it seems that a cell’s enzymes are capable of actively manipulating DNA to do this or that. A genome consists largely of semi-stable genetic elements that may be rearranged or even moved around in the genome thus modifying the information content of DNA.’ The central dogma of the 1950s, as a general principle of biology, has therefore been progressively undermined until it has become useless as support for the Modern Synthesis (Werner, 2005; Mattick, 2007; Shapiro, 2009) or indeed as an accurate description of what happens in cells. As Mattick (2012) says, ‘the belief that the soma and germ line do not communicate is patently incorrect.’”

Beurton PJ, Falk R & Rheinberger H.-J. (2008). The Concept of the Gene in  Development and Evolution: Historical and Epistemological Perspectives. Cambridge University Press, Cambridge, UK.

Mattick JS (2007). Deconstructing the dogma: a new view of the evolution and genetic programming of complex organisms. Ann N Y Acad Sci 1178, 29–46. http://www.ncbi.nlm.nih.gov/pubmed/19845626

Mattick JS (2012). Rocking the foundations of molecular genetics. Proc Natl Acad Sci USA109, 16400–16401 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3478605/

Shapiro JA (2009). Revisiting the central dogma in the 21^st century. Ann N Y Acad Sci 1178, 6–28. http://www.ncbi.nlm.nih.gov/pubmed/19845625

Werner E (2005). Genome semantics, in silico multicellular systems and the Central Dogma. FEBS Lett 579, 1779–1782. http://www.ncbi.nlm.nih.gov/pubmed/15763551

It is important to note that Crick’s original statement of the dogma (made in 1958, and repeated in 1970) was qualified in a very important respect:

“The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. It states that such information cannot be transferred back from protein to either protein or nucleic acid.”

I have italicised “such information” to highlight this important qualification. The statement does not exclude control information passing from cells to the genome. This must happen to enable the same genome to be used to generate many different cell types.