Since the 1950s, studies of the molecular biology of the gene have provided new answers to the fundamental questions about the mechanism of inheritance and the relationship between genes and gene products. Once scientists were able to identify DNA as the genetic material and a model for the three-dimensional structure of DNA was proposed, molecular biologists were able to investigate the biochemical basis of gene structure and function.

The term "genetics" was coined at the beginning of the twentieth century to separate new forms of scientific inquiry from previous studies of generation, inheritance, or heredity. Modern genetics can be seen as the result of the integration of three lines of investigation: classical breeding tests, cytology, and biochemistry. Cytological studies became very sophisticated during the 1930s with the development of ultraviolet microspectrophotometry and special staining techniques. Ingenious use of such techniques...