Which scientists developed the double helix model of DNA?

• A. Darwin and Wallace
• B. Miescher and Chargaff
• C. Franklin and Wilkins
• D. Watson and Crick

Answer: (D)

Understanding who first proposed the DNA double helix helps connect the pieces scientists had gathered about genetics. James Watson and Francis Crick built the first widely accepted 3D model of DNA in 1953, showing two long strands wound into a right-handed helix with a sugar–phosphate backbone on the outside and paired bases on the inside. Their model fit the idea that genetic information is stored in sequence and could be replicated, and it explained why base pairing is so specific: adenine pairs with thymine and cytosine pairs with guanine.

Key supporting ideas came from others: Chargaff's rules showed the A–T and C–G pairing concept, providing crucial guidance for how bases could pair across the strands. X-ray diffraction data obtained by Rosalind Franklin and Maurice Wilkins offered important clues about the dimensions and helical shape, helping to shape the final structure. While Franklin and Wilkins contributed essential data, the full double-helix model is credited to Watson and Crick for integrating these insights into a coherent structure.

By contrast, Darwin and Wallace were pivotal in evolution theory, not DNA structure; Miescher discovered nucleic acids, but did not propose the DNA shape; Franklin and Wilkins provided vital data that guided the model but did not alone publish the double-helix proposal.