Lesson 5 of 8
The DNA story
Goal: Describe how scientists worked out the structure of DNA.
In 1953, the work of four scientists showed the shape of DNA: a double helix.
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Rosalind Franklin
She fired X-rays at DNA and photographed the pattern they made.
In 1952 her laboratory took Photo 51. Its X shape showed that DNA is a helix.
Maurice Wilkins
He began the X-ray work on DNA at King’s College London.
He showed Photo 51 to James Watson. Franklin did not know.
James Watson and Francis Crick
In Cambridge, they used the X-ray results to build a model of DNA.
Their model of 1953 was a double helix. It fitted all the evidence.
- A double helix is two strands twisted round each other, like a twisted ladder.
- The Nobel Prize for this work went to Watson, Crick and Wilkins in 1962. Franklin had died in 1958. Her part in the discovery became widely known only later.
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Key words in this lesson
DNA The chemical that holds genetic information
Double helix The shape of DNA: two strands twisted together