ALL LIVING cells contain long DNA molecules that carry genetic information in their base sequences. These molecules must be read so that proteins can be made, and they must also be duplicated and separated from one another so that cells can divide. Furthermore, if a cell's DNA suffers damage, it must be repaired. These essential processes are carried out by enzymes proteins that catalyse biochemical reactions that "walk" along the DNA double helix. So where does physics come in?
This cellular machinery must be considered from a biomechanical as well as a biochemical point of view, and this requires us to understand the micromechanical properties of DNA itself. Furthermore, since these DNA-processing machines operate at the nanometre scale with energies that are comparable to single thermal fluctuations, statistical mechanics is a key tool in analysing their behaviour.
In the March issue of Physics World, John F Marko and Simona Cocco explain how combining biochemistry with physical concepts and instrumentation is helping researchers to understand the properties of DNA.