Toward a Biology Worthy of Life > Getting Over the Code Delusion > Brief excerpt
A project by Stephen L. Talbott

DNA is not a one-dimensional sequence

There are two grooves (the major and minor grooves) running the length of the DNA double helix, and proteins that recognize an exact sequence of nucleotide bases typically do so in the major groove. However, many proteins bind to DNA in highly selective ways that are not determined by an exact sequence. Recent work has shown that the minor groove may be compressed so as to enhance the local negative electrostatic potential. Regulatory proteins “read” the compression and the electrostatic potential as cues for binding to the DNA. The “complex minor-groove landscape” (Rohs et al. 2009) is affected by the DNA sequence, as well as by associated proteins; however, regulatory factors “reading” the landscape can hardly do so according to a strict digital code. By musical analogy: it’s less a matter of identifying a precise series of notes than of recognizing an improvisation upon a melodic motif...

The lesson in all this, according to bioinformatics researcher, Tom Tullius, has to do with what we lose when we simplify DNA to “a one-dimensional string of letters”. It’s remarkable how readily the historical shift from direct observation of organisms to instrumental read-outs of molecular-level processes encouraged a forgetfulness of material form and substance in favor of abstract codes fit for computers.

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