Part II
The background for the work of the four scientists was formed by several scientific breakthroughs: the progress made by X-ray crystallographers in studying organic macromolecules; the growing evidence supplied by geneticists that it was DNA, not protein, in chromosomes that was responsible for heredity; Erwin Chargaff's experimental finding that there are equal numbers of A and T bases and of G and C bases in DNA; and Linus Pauling's discovery that the molecules of some proteins have helical shapes arrived
