Diffusion may keep big knots out of DNA
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/05/knots_free.jpg?fit=860%2C460&ssl=1)
Snapshots of a new computer simulation, left, show how two knots along a strand of DNA can slide past one another without becoming entangled. A simplified represenation, right, shows how the red knot loosens and the green knot spreads along one of the loops to pass through.
B. Trefz et al/PNAS 2014