John Ellis was a leader in the field of chloroplast biogenesis. He studied the biochemistry of the development of chloroplasts in higher plants. In 1980 Ellis discovered the first molecular chaperone. He found that in chloroplasts unassembled subunits of the rubisco complex were associated with another protein which turned out to be a chaperone. These seminal experiments foreshadowed the discoveries of Horwich and Hartl. Ellis subsequently made substantial contributions to the concept of molecular chaperones which are required to assist a variety of cellular processes in all types of cells.

Dr. Ellis earned his doctorate in 1960 from King's College, London for research on transamination reactions with Professor Davies. Postdoctoral studies were done at Oxford in the Biochemistry Department on sulfate reduction in bacteria with Professor Pasternak. In 1964 Dr. Ellis joined the Departments of Botany and Biochemistry at the University of Aberdeen. He moved to the newly founded Department of Biological Sciences at the University of Warwick in 1970 as Senior Lecturer and Head of the Chloroplast Research Group. In 1976 was awarded a Personal Chair in the department and in 1983 was elected to the Royal Society.