Oswald Avery showed in 1943 that DNA was likely the genetic material of the chromosome, not its protein; the issue was settled decisively with the 1952 Hershey–Chase experiment—one of many contributions from the so-called phage group centered around physicist-turned-biologist Max Delbrück.
Nel 1953 James D. Watson e Francis Crick, sulla base del lavoro di Maurice Wilkins e Rosalind Franklin, ipotizzarono che la struttura del DNA fosse una doppia elica.