Franklin is a biochemist by training (Ph.D. in Comparative Biochemistry, U.C. Berkeley, 1955), but in his own mind he is a physiologist, a cell physiologist. It is the machinery of life, not its molecular constituents, that continues to fascinate him. As a graduate student he came under the influence of the great microbiologist Roger Stanier, from whom he learned that bacteria are the smallest creatures and the simplest; if you would understand life, study bacteria, not rats.
He finished his thesis on the degradation of cholesterol to bile acids in the rat, and then re-branded himself as a microbial physiologist (quite undeterred by his lack of any substantial qualifications in that field).
For thirty years he served on the research staff of the National Jewish Hospital and Research Center in Denver, and concurrently on the faculty of the University of Colorado School of Medicine, ending up as Professor of Biochemistry, Biophysics and Genetics. In 1989 he moved to Colorado State University, and retired from there in 2000 as Professor Emeritus of Biochemistry and Molecular Biology. During all that time he was largely free to pursue research on fundamental problems of his own choosing.
The quest led to a prolonged engagement with Peter Mitchell and the revolution in bioenergetics sparked by his Chemiosmotic Theory; then to the orientation of biochemical processes in cellular space, and ultimately into cell morphogenesis. It generated a lengthy string of research papers and literature reviews, and also three books. Evolution has long been one of his peripheral interests, and has become central during the past decade.