What is the gene made of?

In some ways, asking the question 'Why did Astbury not solve the structure of DNA from Beighton's photograph?' is a little unfair because this makes a judgement on the science of the past in terms of what we currently know.

Firstly, in the early 1950s, no-one was exactly sure as to the material nature of the gene. Was it a molecule? If so, what kind of molecule? In 1944, the eminent physicist Erwin Schrodinger had published a little book called 'What is Life?' in which he proposed that any material component of the gene must have two key properties:
  • It must be thermodynamically stable

  • It must exhibit a high degree of structural variation

Of all the different types of biological molecule, one candidate fitted both these criteria - proteins.

Astbury certainly believed that, by virtue of their structural complexity, proteins might be able to carry genetic information, for in a paper presented in 1938, he wrote:

'Knowing what we now know from X-ray and related studies of the fibrous proteins, how they are built from long polypeptide chains with linear patterns drawn to a grand scale, how these chains can contract and take up different configurations by intramolecular folding, how the chain-groups are penetrated by, and their side-chains react with, smaller co-operating molecules, and finally how they can combine so readily with nucleic acid molecules and still maintain the fibrous configuration, it is but natural to assume, as a first working hypothesis at least, that they form the long scroll on which is written the pattern of life [41]. No other molecules satisfy so many requirements.'

(Astbury & Bell, 1938 p.117)

In addition to speculation that proteins might carry genetic information, there was also the possibility that the gene might be a nucleoprotein

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