The micromechanics of DNA

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?