The Picture That Helped Reveal DNA
How can a photograph show the shape of something too small to see with an ordinary microscope? For scientist Rosalind Franklin and her colleagues, the answer involved X-rays and a careful study of patterns.
Franklin was born on July 25, 1920. At King’s College London, she studied DNA, the molecule that carries instructions for living things. In the laboratory, Franklin examined diffraction patterns: marks made when X-rays bounced off a prepared sample of DNA and spread in different directions. The positions of the marks held clues about how the molecule was arranged.
In 1952, graduate student Raymond Gosling, working under Franklin’s supervision, produced an especially clear X-ray diffraction image known as Photo 51. Its X-shaped pattern was evidence that DNA had a helical, or spiral-like, structure. Franklin’s measurements and analysis also provided important information about the molecule’s dimensions.
Other researchers were studying DNA too. Maurice Wilkins worked on DNA at King’s College London. James Watson and Francis Crick used evidence from several sources, including Franklin’s work and Photo 51, as they built a model of DNA. Their 1953 model showed DNA as a double helix: two strands twisted around each other. Franklin’s data were shared with Watson and Crick without her knowledge, a fact that matters when giving credit for the discovery.
- colleagues:
- People who work with one another.
- supervision:
- Guidance and oversight of someone’s work.
- analysis:
- A careful study of information to understand it.
- dimensions:
- Measurements that describe the size of something.
- evidence:
- Information that helps support an idea or conclusion.
- model:
- A representation used to show or explain something.
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Preview questions from this passageShowHide
- 1How did X-rays help Franklin study something too small to see with an ordinary microscope?
- 2What did the X-shaped pattern in Photo 51 suggest about DNA?
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About this explanatory article passage for Upper Elementary
“The Picture That Helped Reveal DNA” is a explanatory article reading passage about DNA research, written for Upper Elementary. It takes about 2 minutes to read (252 words) and comes with an interactive quiz and a printable worksheet with comprehension questions and an answer key.