Multiple choice general knowledge The molecular structure of DNA was first determined by Sir Isac Newton Watson and Crick Gorge smith and Halis leavy Dr.Thomas Bernard Reveal answer Fill a bubble to check yourself B Correct answer Explanation James Watson and Francis Crick discovered the double-helix structure of DNA in 1953 at Cambridge University. They used Rosalind Franklin's X-ray diffraction data (Photo 51) to deduce that DNA has a twisted ladder structure with paired bases.