Marie M. Daly developed a way to separate the bases of DNA and RNA using a method called column chromatography. This allowed her to confirm that adenine always pairs with thymine and guanine with cytosine, and she also showed that these four bases—A, T, G, C—are the only significant components in DNA. Additionally, her doctoral research improved our understanding of how enzymes, which are proteins that can speed up biochemical reactions, break down food by studying the effects of pancreatic amylase on corn starch. Throughout her career, Daly explored how proteins are made, investigated the connection between high cholesterol and heart disease, and studied how sugars and other substances affect artery health.