Remarkably, living cells are able to package a jumble of DNA over two meters in length into tidy, tiny chromosomes while preparing for cell division. However, scientists have been puzzled for decades about how the process works. Researchers from the Kavli Institute of Delft University and EMBL Heidelberghave now isolated and filmed the process, and witnessed in real time how a single protein complex called condensin reels in DNA to extrude a loop. By extruding many such loops in long strands of DNA, a cell effectively compacts its genome so it can be distributed evenly to its two daughter cells. The scientists published their findings in Science.