Leland H. "Lee" Hartwell helped pioneer the development of yeast as a model system for genetics in the mid-1960s. Hartwell then used that system to help decipher the cell cycle, and to discover in the 1980s an important pathway in cancer development. Through his hypothesis on checkpoints, he proposed a genetic link between disruptions of the normal cell cycle and cancer cell proliferation. Hartwell, along with R. Timothy Hunt and Paul Nurse, shared the 2001 Nobel Prize in medicine or physiology for their research in genetic control of cell cycle regulation.

Born in Los Angeles, California, Hartwell first began to explore his interests in science, and particularly physics and math, with the help of his high school teachers. After a year at Glendale Junior College, he transferred to the California Institute of Technology (CalTech) as an undergraduate student and spent much of his time conducting research on phages...