Jewel Isadora Cobb (later Jewel Plummer Cobb) was born in 1924 to Carriebel (Cole) and Frank V. Plummer in Chicago, Illinois. The family came from a line of medical and science professionals. Cobb's mother was a dancer and taught physical education, while her father was the first Black graduate of Cornell University to hold a doctorate in medicine. Frank Plummer's father graduated from Howard University in 1898, after being freed from enslavement, and later became a practicing pharmacist.
During high school, Cobb's teachers encouraged her developing interest in biology. Cobb enrolled at the University of Michigan in 1942; however, segregated housing policies did not allow Black students to live on campus, and she transferred to Talladega College, a historically Black institution in Alabama. At Talladega, Cobb became a lifelong member of the Alpha Kappa Alpha sorority. She graduated with a Bachelor of Arts in biology in 1945. Cobb continued her studies, earning a Master of Science in 1947 and later a PhD in cellular biology in 1950 from New York University (NYU). While she was initially denied the fellowship at NYU, Cobb was admitted after her interview. Her dissertation, "Mechanisms of Pigment Formation," examined melanin pigment granule formation in vitro using the enzyme tyrosinase. In 1949, Cobb was appointed to the role of independent investigator at Woods Hole Marine Biological Laboratory in Falmouth, Massachusetts.
After earning her PhD, Cobb continued to teach at NYU and was appointed to a teaching fellowship in the Biology department. Cobb held postdoctoral positions at the Harlem Hospital Cancer Research Foundation, Columbia University College of Physicians and Surgeons, and the National Cancer Institute.
In 1952, she was hired as an instructor in anatomy at the University of Illinois College of Medicine, a position she held until 1954. Cobb returned to New York, where she taught and lectured at Hunter College and NYU. A tenure as head of the biology laboratory at Sarah Lawrence College from 1960 to 1969 followed. While there, Cobb conducted undergraduate research for participants in the National Science Foundation.
Cobb also taught at Connecticut College in New London, where she served as the institution's first Black Dean of Arts and Sciences. While serving in this role, Cobb established a scholarship program that provided financial assistance to Black students pursuing careers in the sciences.
Due to her expanding role at Connecticut College, Cobb had less time to dedicate to her research. She decided to leave Connecticut College for Douglass College at Rutgers University, where she also served as the College's Dean. Cobb was recommended as a candidate for the President of Hunter College in 1979, but was not selected for the role. Several Black civic groups and women in science organized protests and petitions in support of Cobb's appointment. Had she been selected, Cobb would have been Hunter's first Black president.
Cobb was appointed President of California State University, Fullerton (CSUF) in 1981, where she pursued both private and state financing to improve the campus's facilities. Cobb initiated numerous construction projects, including the completion of several science buildings and the University's first student housing. The residence building is named after Cobb. Enrollment at the college increased after Cobb implemented these measures. However, the University had a strict policy of not employing staff over the age of sixty-five, and Cobb was forced into retirement in 1990.
After leaving CSUF, Cobb continued her work supporting Black students's access to science education. She established the Science Technology Engineering Program (STEP) Up for Youth through California State University, Los Angeles, and the Pueblo Science ASCEND Project.
Cobb was the recipient of many awards, including the 1999 Achievement in Excellence Award from the Center for Excellence, in recognition of her contributions to science and education. She has also served as a board member of numerous organizations, including the National Science Board; Talladega College; and the National Committee on Women in Science and Engineering of the National Academy of Sciences.
Later in life, Cobb became interested in writing her memoir, and through the encouragement of her son Jonathan, she began keeping journals to document remembrances and reflections. During this time, Cobb also developed a strong interest in her family history and conducted extensive genealogical research.
Cobb died in 2017 at her home in New Jersey due to complications of Alzheimer's disease at the age of 92.