By about 1950, some biologists were convinced by the work of Griffith, Avery, and others that DNA is the genetic material. To serve as the genetic material, DNA would have to be able to replicate itself, undergo rare mutations, replicate mutant forms as faithfully as the original forms, and direct the synthesis of other macromolecules in the cell. How could one molecule do all this? Part of the answer emerged in 1953, when James D. Watson and Francis H. C. Crick announced a description of the three-dimensional structure of DNA. This discovery marked a turning point in modern biology. The discovery of the structure of DNA opened the door to understanding how genetic information is stored, faithfully replicated, and altered by rare mutations.