James Watson, co-discoverer of the genetic model of DNA, in his office at Cold Spring Harbor Laboratory in Laurel Hollow, New York, in August 1999. Photograph: Suzanne DeChillo/The New York Times
What is the hereditary information in genes? This fundamental question intrigued Jim Watson at a time when accumulating evidence was pointing to genes being made of DNA and not protein.
The answer is (essentially) the order of just four variants of one type of biological component, known as “bases” (A, C, G, T). This was unsuspected when 24-year-old Watson surprisingly found the bases could bond together in two types of pairs [A:T (T:A), C:G (G:C)].
The American theoretical and physical chemist Jerry Donohue was the unsung hero, as he steered Watson and Francis Crick towards the correct structure of DNA with some crucial information. Watson’s discovery provided the final key for his collaborative trial-and-error model building with Crick. They deduced that DNA is like a twisted ladder, with the base pairs forming the ladder’s rungs.
This structure led to the famous understatement in their 1953 publication in the journal Nature: “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” It did – the correct one – a monumental discovery.
Importantly, Watson’s base pairing scheme is also crucial for RNA, the informational storage molecule in some viruses.
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