Colin Munro MacLeod is recognized as one of the founders of molecular biology for his research concerning the role of deoxyribonucleic acid (DNA) in bacteria. Along with his colleagues Oswald Avery and Maclyn Mc Carty, MacLeod conducted experiments on bacterial transformation which indicated that DNA was the active agent in the genetic transformation of bacterial cells. His earlier research focused on the causes of pneumonia and the development of serums to treat it. MacLeod later became chairman of the department of microbiology at New York University; he also worked with a number of government agencies and served as White House science advisor to President John F. Kennedy.

MacLeod, the fourth of eight children, was born in Port Hastings, in the Canadian province of Nova Scotia. He was the son of John Charles MacLeod, a Scottish Presbyterian minister, and Lillian Munro MacLeod, a schoolteacher. During his childhood, MacLeod moved...