Which scientist used X-ray crystallography to examine the structure of the DNA molecule?

Which scientist used X-ray crystallography to examine the structure of the DNA molecule?

• A. Rosalind Franklin
• B. James Watson
• C. Francis Crick
• D. Erwin Chargaff

Answer: (A)

X-ray crystallography lets scientists see the arrangement of atoms in a molecule by analyzing how X-rays diffract through crystallized samples. Rosalind Franklin famously used this technique on DNA fibers and produced high-quality diffraction images that showed an unmistakable x-shaped pattern, signaling a helical structure and suggesting a long, two-stranded molecule with consistent dimensions. This direct imaging of DNA’s form is what identifies her as the scientist who used X-ray crystallography to examine DNA. The other figures contributed in important ways — Chargaff established base-pairing rules from chemical composition, while Watson and Crick built a model of the DNA structure using Franklin’s data alongside other information — but they did not perform the primary X-ray crystallography analysis themselves.

X-ray crystallography lets scientists see the arrangement of atoms in a molecule by analyzing how X-rays diffract through crystallized samples. Rosalind Franklin famously used this technique on DNA fibers and produced high-quality diffraction images that showed an unmistakable x-shaped pattern, signaling a helical structure and suggesting a long, two-stranded molecule with consistent dimensions. This direct imaging of DNA’s form is what identifies her as the scientist who used X-ray crystallography to examine DNA. The other figures contributed in important ways — Chargaff established base-pairing rules from chemical composition, while Watson and Crick built a model of the DNA structure using Franklin’s data alongside other information — but they did not perform the primary X-ray crystallography analysis themselves.