Who developed the double helix model of DNA?

• A. Amino acid
• B. Essential amino acids
• C. Codons
• D. Watson and Crick

Answer: (D)

Watson and Crick proposed the double helix in 1953, drawing on X-ray diffraction data and established base-pairing rules to build a coherent model. Their idea showed two long strands of sugar-phosphate backbone winding around each other in a right-handed spiral, with the nitrogenous bases paired inside the structure. Adenine pairs with thymine and cytosine pairs with guanine, held together by hydrogen bonds, and the two strands run antiparallel. This arrangement explains how genetic information is stored in a sequence of bases and how the molecule can be accurately copied during replication because each strand can serve as a template for the other. The other options refer to concepts or molecules, not people, so they don’t describe who developed the model.