Which scientist generated X-ray images of DNA that provided key data about its structure?

• A. James Watson
• B. Rosalind Franklin
• C. Maurice Wilkins
• D. Linus Pauling

Answer: (B)

X-ray diffraction data reveal the three-dimensional shape of molecules. Rosalind Franklin produced key X-ray images of DNA, most famously Photo 51, which showed a cross-shaped pattern indicating a regular helix. From this pattern, scientists could infer the helix diameter (about 2 nanometers) and the spacing of bases along the strand (about 0.34 nanometers per base pair, with roughly 10 base pairs per turn). This evidence was crucial for determining that DNA is a double helix and guided the construction of the correct model. Watson and Crick used Franklin’s data to finalize their model, while Linus Pauling proposed a different structure without these diffraction images. So the scientist who generated the essential X-ray images is Rosalind Franklin.