Helen Conrad Davies, 97, an award-winning scientist and professor emeritus of microbiology at the University of Pennsylvania, a vocal advocate for racial equality and women’s rights, and a revered mentor who sang to her students about infectious diseases, died Wednesday, March 23, of respiratory failure at the Hospital of the University of Pennsylvania.

Professor Davies, who insisted that everyone call her Helen, was an expert on bacterial energetics, electron transfer, and the cytochrome system. A trailblazer from the start, she was the only woman in her college biology and chemistry class, the first female faculty member in Penn’s microbiology department, and the department’s first female full professor.

She joined Penn’s department of physical biochemistry in 1960; contributed to countless projects and studies about cellular respiration, virulence factors, and other topics; and wrote and cowrote many important papers.

Demonstrative, talented, and creative, she embraced teaching as much as research and, using her experience as a nightclub singer in college, became known in the classroom as the “singing professor.” To help students remember complex concepts, she created amusing lyrics that explained the basics of infectious diseases, set them to tunes of popular songs, and belted them out in class.

“Leprosy,” set to the Beatles’ song “Yesterday,” began: “Leprosy, bits and pieces falling off of me. But it isn’t the toxicity. It’s just neglect of injury.”

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Even now, former students break into song when her name is mentioned, and she once performed a few of her “infectious” hits for fun at a New York nightclub. “I want people to love the subject matter,” she told The Inquirer in 2001. “Medical students need to memorize certain things.”

In 2008, Penn student Kiona Allen told The Inquirer: “She’s like my favorite person in the world.”

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Over her seven-decade career, Professor Davies served as academic coordinator of Penn’s microbiology department, associate dean for student affairs in its Perelman School of Medicine, and a trustee at Pennsylvania State University. She retired in 2021, and her portrait hangs at the entrance to the microbiology department in Penn’s Johnson Pavilion.

In 1996, William Kelley, then the CEO of the Penn Medical Center and Health System, told Professor Davies as her portrait was unveiled: “As a teacher, you did not merely meet a standard, you set it.”

Professor Davies received 39 major teaching awards and countless others, including the 1999 Lifetime Mentor Award of the American Association for the Advancement of Science. In 2001, she became the first woman to receive the American Medical Student Association’s National Excellence in Teaching Award.

She marched in 1965 with the Rev. Dr. Martin Luther King Jr. in Alabama and Washington, was a leader for racial equality and women’s rights at Penn and elsewhere, and won the 2004 Helen O. Dickens Lifetime Achievement Award from Women of Color at Penn.

She was a founder, president, and member of many national scientific organizations, and the Association for Women in Science Educational Foundation created the Helen and Robert Davies Award in 1978.

Born Helen Rogoff on Feb. 14, 1925, in Manhattan, Professor Davies graduated from Hunter College High School for Intellectually Gifted Young Ladies, now Hunter College High School, at 15 and from Brooklyn College in 1944. She was a singer and performed on stage when she was young and in nightclubs during her college years.

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She earned a master’s degree in biochemistry at the University of Rochester in 1950 and, while raising two sons, got her doctorate in physical biochemistry at Penn in 1960. She married Matthew Conrad in 1944 and had sons Daniel and Richard. They later divorced. He died earlier.

She married Robert Davies, an adventurer and professor of biophysics at Penn, in 1961, and they traveled the world together, climbing mountains and exploring caves. He died in 1993.

She loved live music, liked to have breakfast with the gorillas at the Philadelphia Zoo, and lived for years in Ware College House at Penn with 500 undergraduates. “I just love the students so much I want to be part of them,” she said in a recent online interview.

“Helen would look at you with her bright blue eyes gleaming, and you felt you could do anything,” said longtime friend Emilie Anderson. “You felt love.”

In addition to her sons, Professor Davies is survived by other relatives. A sister died earlier.

A celebration of life is to be held later.

Donations in her name may be made to the Helen Conrad Davies Memorial Fund, University of Pennsylvania, Office of the Treasurer, P.O. Box 71332, Philadelphia, Pa. 19176.