When DNA gets twisted into a knot it doesn't work. Fortunatly our cells have enzymes that fix the problem by cutting the DNA, straightening it out and splicing it back together. So knots can be very, very important. So important that mathematicians created the field of knot theory to try to get a handle on knots and make them simpler to understand. But to hear Hank tell it you may think they're making it more complicated.
—David Foss