DNA replication is a complex process in which a helicase ring separates the DNA molecule’s two entwined and encoded strands, allowing each to precisely reproduce its missing half. Until recently, however, researchers have not understood how the helicase—a donut-shaped enzyme composed of six identical proteins—is able to thread just one of the strands when they are bound together. Now, new research from scientists at The Graduate Center of The City University of New York, its Advanced Science Research Center (ASRC), and The City College of New York (CCNY) has solved the mystery.