[2] Daly made important contributions in four areas of research: the chemistry of histones, protein synthesis, the relationships between cholesterol and hypertension, and creatine's uptake by muscle cells.

She lived at home to save money and graduated magna cum laude from Queens College with her bachelor's degree in chemistry in 1942.

[4] Daly worked as a laboratory assistant at Queens College while studying at New York University for her master's degree in chemistry, which she completed in 1943.

[8][9][5] [2] Daly worked as a physical science instructor at Howard University, from 1947 to 1948 while simultaneously conducting research under the direction of Herman Branson.

After being awarded an American Cancer Society grant to support her postdoctoral research, she joined Alfred E. Mirsky's group at the Rockefeller Institute, which studied the cell nucleus and its constituents.

[8] This was the start of a seven-year research program at the Rockefeller Institute of Medicine, where Daly examined how proteins are constructed in the body.

[3] Daly developed methods for separating out the nuclei of tissues and measuring the base composition of purines and pyrimidines in desoxypentose nucleic acids.

[24][25] Using radiolabeled amino acid glycine, she was able to measure how protein metabolism changed under feeding and fasting conditions in mice.

She was the first to establish that hypertension was a precursor to atherosclerosis,[12] and the first to identify a relationship between cholesterol and clogged arteries,[27] an important discovery in understanding how heart attacks occur.

She showed that high cholesterol intake in diet led to clogged arteries, and that hypertension accelerated this effect.

[5] Daly's interest in science was also influenced by her father, who had attended Cornell University with the intention of becoming a chemist, but had been unable to complete his education due to a lack of funds.

Years later, she started a Queens College scholarship fund in his honor to assist minority students majoring in chemistry or physics.

[39] Every year guest speakers are invited to give a lecture highlighting diversity and contribution of minorities to science.