In Front, not Behind (IMAGE) Rockefeller University Caption Previously (left), the replisome's two polymerases (green) were assumed to be below the helicase (tan), the enzyme that splits the DNA strands. The new images reveal one polymerase is located at the front of the helicase, causing one strand to loop backward as it is copied (right). Credit Brookhaven National Laboratory Usage Restrictions Image may be used only to illustrate the research described in the accompanying release. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.