Inside the nucleus of each human cell are two metres of DNA, bundled tightly into 46 chromosomes.
The long molecules move constantly, adjusting to the needs of the cell and bringing certain genes into contact with each other so they can work together.
The video above, produced by Science based on research published in the journal Cell, shows a computer rendering of a considerably sped-up version of this process, and lets us watch how the three-dimensional structure changes over time.
This shows how one protein, cohesin, helps to orchestrate the movements. By removing and then adding cohesin, researchers made specific DNA loops that disappear and then reappear.
Cohesin only explains part of the process, though. It brings genes on the same chromosome into contact with each other, but another mechanism as yet unknown does the job for genes from different chromosomes.