Free levelled English reading practice. Read for meaning first, then use the full Speed Reading tool to time yourself and track your progress.
Inside nearly every cell in the human body is DNA, a molecule carrying genetic information. Understanding its structure became one of the great scientific achievements of the twentieth century. Scientists already knew that DNA was important, but its three-dimensional form was unclear. In the early 1950s, several researchers were investigating the problem. At King's College London, Rosalind Franklin used X-ray diffraction to study DNA fibres. Her exceptionally clear experimental work, including the famous image known as Photo 51, provided crucial evidence that DNA had a helical structure. At the University of Cambridge, James Watson and Francis Crick built physical models as they tried to determine how the molecule fitted together. They also drew on findings produced by Franklin, Maurice Wilkins and other scientists. In 1953, Watson and Crick proposed the double-helix model: two strands winding around each other, with paired chemical bases inside. The structure helped explain how genetic information could be copied. In 1962, Watson, Crick and Wilkins received the Nobel Prize in Physiology or Medicine. Franklin had died of cancer in 1958, and Nobel Prizes are not awarded posthumously. Modern accounts increasingly emphasise her essential contribution and the complicated history of how her data were shared and used. The discovery opened the way to modern molecular biology, genetic testing, genome sequencing and many medical advances.
Comprehension questions
What method did Rosalind Franklin use?
What did Photo 51 help show?
What model did Watson and Crick propose?
Why did Franklin not share the 1962 Nobel Prize?
What does the passage say about Franklin’s contribution?
