a timeline of discoveries

  • Friedrich Miescher discovers DNA in his preparations of white blood cells extracted from the pus in surgical bandages. He calls it ‘nuclein’.

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    William Henry Bragg and son William Lawrence Bragg lay the foundations for the field of X-ray crystallography when they realise they can infer the structure of crystals from the patterns of scattered X-rays.

  • Phoebus Levene discovers nucleotides – the combination of a sugar, base and phosphate group – and suggests they form short lengths of DNA called ‘tetranucleotides’.

  • Florence Bell arrives in William Astbury’s lab and takes the first X-ray images of DNA. Astbury makes an attempt at a structure the following year.

  • Oswald Avery, Colin MacLeod and Maclyn McCarty demonstrate that DNA is the material controlling inheritance.

  • Rosalind Franklin takes ‘Photo 51’, a highly detailed image of the ‘B’ or hydrated form of DNA. The photo is later seen by James Watson without her knowledge.

  • James Watson and Francis Crick propose a model for the structure of the DNA molecule.

  • DNA from two different organisms is spliced together for the first time by Paul Berg, paving the way for genetic modification and GM foods.

  • Dolly the sheep is born. Dolly is the first mammal cloned from a non-embryonic cell. Her DNA is identical to the sheep she was cloned from.

  • After £3bn and 13 years of work, the Human Genome Project is completed and the entire genome of a human being is published. Today, people can get their genome sequenced in a matter of hours for around £100.

  • President Barack Obama announced plans to sequence the genomes of one million US citizens to help personalise medicine and learn more about rare diseases. Authors