Researchers mapped where DNA first opens and how a helicase gate may release one strand as genome copying begins. DNA opens at the ring junctionTo prepare DNA for copying, cells activate molecular machines called helicases, which pull apart the two strands of the double helix. “DNA replication is fundamental to every cell division, yet we still did not fully understand how it begins inside living cells. These temporary states help explain how inactive protein complexes are reorganized into fully functioning DNA copying machines. Accurate DNA replication is necessary for genome stability, while mistakes can leave sections of DNA damaged or incompletely copied.