Life's Greatest Secret Read Online Free

Tatum, Beadle followed Muller’s approach and irradiated
Neurospora
spores with X-rays in the hope of producing mutant fungi that required added vitamins to survive, thereby opening up the possibility of studying the genetics of vitamin biosynthesis. Beadle and Tatum soon found mutants that were unable to synthesise particular vitamins, and published their findings in 1941. 35 Each mutation affected a different enzymatic step in the vitamin’s biosynthetic pathway – this was experimental proof of the widely held view, going back to the beginning of the century, that genes either produced enzymes or indeed simply were enzymes. 36 When Beadle presented their findings at a seminar at the California Institute of Technology (Caltech) in Pasadena, the audience was stunned. He spoke for only thirty minutes and then stopped. There was a nonplussed silence – one member of the audience recalled:
    We had never heard such experimental results before. It was the fulfilment of a dream, the demonstration that genes had an ascertainable role in biochemistry. We were all waiting – or perhaps hoping – for him to continue. When it became clear that he actually was finished, the applause was deafening.
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    In the following year, Beadle and Tatum suggested that ‘As a working hypothesis, a single gene may be considered to be concerned with the primary control of a single specific chemical reaction.’ 38 A few years later, a colleague refined this to the snappier ‘one gene, one enzyme hypothesis’. There was support for this view from work on human genetic diseases such alkaptonuria – in 1908 Archibald Garrod had suggested that this disease might involve defective enzyme production. But Beadle and Tatum’s hypothesis met with opposition at the time, partly because it was known that genes have multiple effects, while their hypothesis – or rather, the ‘one gene, one enzyme’ catch-phrase by which it came to be known – seemed to suggest that each gene did only one thing: control an enzyme. 39
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    Trinity College sits in the heart of Dublin, its grey three-storey neoclassical buildings positioned around lawns and playing fields. At the eastern end of the campus there is another grey building, built in 1905 in a rather different style. This is the Fitzgerald Building, or the Physical Laboratory as it is called in deeply engraved letters on the stone lintel. On the top floor there is a lecture theatre, and in the late afternoon of the first Friday of February 1943, around 400 people crowded onto the varnished wooden benches. According to
Time
magazine, among those lucky enough to get a seat were ‘Cabinet ministers, diplomats, scholars and socialites’, as well as the Irish Prime Minister, Éamon de Valera. 40 They were there to hear the Nobel Prize-winning physicist Erwin Schrödinger give a lecture with the intriguing title ‘What is life?’ The interest was so great that scores of people were turned away, and the lecture had to be repeated the following Monday. 41
    Schrödinger had arrived in Dublin after fleeing the Nazis – he had been working at Graz University in Austria when the Germans took over in 1938. Although he had a reputation as an opponent of Hitler, Schrödinger published an accommodating letter about the Nazi takeover, in the hope of being left alone. This tactic failed, and he had to flee the country in a hurry, leaving his gold Nobel medal behind. De Valera, who was interested in physics, offered Schrödinger a post in Dublin’s new Institute for Advanced Studies, and the master of quantum mechanics found himself in Ireland. 42
    On three consecutive Fridays, 56-year-old Schrödinger walked into the Fitzgerald Building lecture theatre to give his talks, in which he explored the relation between quantum physics and recent discoveries in biology. 43 His first topic was the way in which life seems to contradict the second law of thermodynamics. Since the nineteenth century it has been known that, in a