Which scientists are credited with the discovery of the DNA double helix structure?

• A. Rosalind Franklin and Maurice Wilkins
• B. James Watson and Francis Crick
• C. Linus Pauling
• D. Erwin Chargaff

Answer: (B)

Understanding the discovery of the DNA double helix hinges on how the structure explains both stored information and faithful replication. Watson and Crick, in 1953, built a model that fit the available data: DNA is composed of two long strands arranged in a helix, with the sugar–phosphate backbones on the exterior and the bases paired inside. The crucial insight is the specific pairing of bases—A with T and G with C—which provides a simple and accurate mechanism for copying genetic information. This pairing also aligns with Chargaff’s rules, which show equal amounts of complementary bases in any given DNA sample. The X-ray diffraction data, notably the hint of a helical structure with a consistent width, came from Franklin’s work and was shared with Watson and Crick, helping them perfect the model. Linus Pauling’s rejected idea of a triple-helix structure didn’t fit the evidence, so it didn’t become the correct model. In short, the double-helix model that unifies the helical shape, antiparallel strands, and specific base pairing best explains how DNA stores information and is copied, which is why Watson and Crick are credited with the discovery.