In 1948, a dynamic junior member of the Johns Hopkins Biology Department, William McElroy, became the first director of the McCollum—Pratt Institute for the Investigation of Micronutrient Elements. The Institute was founded at the university to further studies into the practicalities of animal nutrition. Ultimately, however, the Institute reflected McElroy's vision that all biological problems, including nutrition, could be best investigated through basic biochemical and enzymes studies. The Institute quickly became a hub of biochemical research over the following decade, producing (...) foundational work on metabolism and a respected series of symposia. In this paper, I argue that McElroy's biochemical vantage on biology also permeated the traditionally morphological and embryological Biology Department at Hopkins. Largely due to the activity of McElroy and the Institute, the faculty, course offerings, and research underwent a radical reorientation toward biochemistry and molecular biology in the 1950s, even while maintaining a commitment to developmental biology. While the history of postwar biology is often told as the ascendancy of the "new" biology over "traditional" biology, the case of McElroy and the McCollum—Pratt Institute affords an opportunity for historical examination of biochemical and molecular science as a lens through which all branches of biology at an institution were reconceived and unified. (shrink)