The story behind DNA’s double helix
The notorious race to uncover the structure of DNA, the molecule of inheritance, began in 1951, when American biologist James Watson arrived at the University of Cambridge. Here he met Francis Crick, an English physicist and the two began building scale models to test their ideas of what DNA’s appearance might be.
Meanwhile, two scientists at King’s College London called Maurice Wilkins and Rosalind Franklin were also studying DNA. They were attempting to crystallise the molecule to make an x-ray pattern of it. They hoped this would provide important clues about its structure.
Although the two institutions were effectively competing against each other, Francis Crick (University of Cambridge) and Maurice Wilkins (King’s College London) communicated regularly. Letters sent from Wilkins to Crick reveal their close personal relationship.
It was Rosalind Franklin’s famous x-ray image, nicknamed ‘Photo 51’, that finally revealed the structure of DNA in May 1952. The pattern appeared to contain ‘rungs’, like those on a ladder, set between two strands. The fuzzy “X” pattern indicated DNA’s helix shape. In early 1953, Wilkins showed Watson the image, seemingly without Franklin’s knowledge.
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DNA: Celebrate the unknowns | Philip Ball
On the 60th anniversary of the double helix, we should admit that we don’t fully understand how evolution works at the molecular level, suggests Philip Ball.
This week’s diamond jubilee of the discovery of DNA’s molecular structure rightly celebrates how Francis Crick, James Watson and their collaborators launched the ‘genomic age’ by revealing how hereditary information is encoded in the double helix. Yet the conventional narrative — in which their 1953 Nature paper led inexorably to the Human Genome Project and the dawn of personalized medicine — is as misleading as the popular narrative of gene function itself, in which the DNA sequence is translated into proteins and ultimately into an organism’s observable characteristics, or phenotype.
Sixty years on, the very definition of ‘gene’ is hotly debated. We do not know what most of our DNA does, nor how, or to what extent it governs traits. In other words, we do not fully understand how evolution works at the molecular level.
That sounds to me like an extraordinarily exciting state of affairs, comparable perhaps to the disruptive discovery in cosmology in 1998 that the expansion of the Universe is accelerating rather than decelerating, as astronomers had believed since the late 1920s. Yet, while specialists debate what the latest findings mean, the rhetoric of popular discussions of DNA, genomics and evolution remains largely unchanged, and the public continues to be fed assurances that DNA is as solipsistic a blueprint as ever.
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DNA: Celebrate the unknowns | Philip Ball
On the 60th anniversary of the double helix, we should admit that we don’t fully understand how evolution works at the molecular level, suggests Philip Ball.
This week’s diamond jubilee of the discovery of DNA’s molecular structure rightly celebrates how Francis Crick, James Watson and their collaborators launched the ‘genomic age’ by revealing how hereditary information is encoded in the double helix. Yet the conventional narrative — in which their 1953 Nature paper led inexorably to the Human Genome Project and the dawn of personalized medicine — is as misleading as the popular narrative of gene function itself, in which the DNA sequence is translated into proteins and ultimately into an organism’s observable characteristics, or phenotype.
Sixty years on, the very definition of ‘gene’ is hotly debated. We do not know what most of our DNA does, nor how, or to what extent it governs traits. In other words, we do not fully understand how evolution works at the molecular level.
That sounds to me like an extraordinarily exciting state of affairs, comparable perhaps to the disruptive discovery in cosmology in 1998 that the expansion of the Universe is accelerating rather than decelerating, as astronomers had believed since the late 1920s. Yet, while specialists debate what the latest findings mean, the rhetoric of popular discussions of DNA, genomics and evolution remains largely unchanged, and the public continues to be fed assurances that DNA is as solipsistic a blueprint as ever.
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