• Gary, R.K. (2004). The concentration dependence of the Delta S term in the Gibbs free energy function: Application to reversible reactions in biochemistry. Journal of Chemical Education, 81, 1599–604.

A detailed explanation of the equations used for calculating free energy change and an exploration of how entropy changes occur as biochemical reactions proceed.

• Westheimer, F.H. (1987). Why nature chose phosphates. Science, 235, 1173–8.

A discussion of why phosphate esters and anhydrides are so common in the living world.

• Dogterom, M. (2001). Cell Biophysics. In Encyclopedia of Life Science. Wiley & Sons Ltd, Chichester. www.els.net [DOI: 10.1038/npg.els.0001271]

A short, slightly more advanced, but interesting article that summarizes thermodynamic and other biophysical constraints such as crowding of molecules that impact on events in the cell.