The cell nucleus, which is around six millionths of a metre in diameter, contains two metres of DNA, a feat which is ‘geometrically equivalent to packing 40 km (24 miles) of extremely fine thread into a tennis ball.’50 That’s not all, since the 46 separate chromosomes (each averaging, if we continue the analogy, the equivalent of over half a mile long), have to be kept distinct and functional, not hopelessly entangled.
