In 1951 and 1952, Alfred Hershey and Martha Chase conducted a series of experiments at the Carnegie Institute of Washington in Cold Spring Harbor, New York, that verified genes were made of deoxyribonucleic acid, or DNA. Hershey and Chase performed their experiments, later named the Hershey-Chase experiments, on viruses that infect bacteria, also called bacteriophages. The experiments followed decades of scientists’ skepticism about whether genetic material was composed of protein or DNA. The most well-known Hershey-Chase experiment, called the Waring Blender experiment, provided concrete evidence that genes were made of DNA. The Hershey-Chase experiments settled the long-standing debate about the composition of genes, thereby allowing scientists to investigate the molecular mechanisms by which genes function in organisms.

The Protein Information Resource, or PIR, is an online, publicly available resource that contains databases of protein sequences and computer programs that support the study of proteins, their functions, evolutionary histories, and interactions with other biomolecules in living organisms. A non-profit research institution called the National Biomedical Research Foundation, or NBRF, established the PIR in 1984. Since proteins were first sequenced in the late 1950s, scientists have used protein sequence data to understand biological functions, interactions, and pathways. Protein sequences contribute to many kinds of research, including genomics, proteomics, and systems biology. From 1984 to 2004, the PIR housed one of the first, free online protein sequence databases and computer programs that allowed searching and comparison of those sequences. During that twenty-year period, scientists could use the PIR to identify an unknown protein and determine its evolutionary history and function, including its role in embryological development.

The Atlas of Protein Sequence and Structure, hereafter the Atlas, was a computerized collection of protein sequences distributed in the form of a paperback book published from 1965 to 1979. Margaret Oakley Dayhoff, a researcher who used computers to study biochemistry, was the primary author. Most editions of the Atlas included chapters of original research and computer programs for analyzing protein-sequence data to determine protein structure and function and derive insights about evolution at the molecular level. Before the establishment of the Atlas, biochemists sometimes published specialized sequence collections for comparative research about a given protein. The Atlas was the first comprehensive collection of all published protein sequences derived from diverse organisms. The Atlas laid the foundation of what is, as of 2026, a leading international protein-sequence database, enabling numerous lines of research, such as predicting the function of unknown proteins, which in turn informs scientific technologies and advances such as gene editing.