ing biological systems function far from equilibrium; in fact, a biological system is at equilibrium only when it is dead! A theory of systems far from equilibrium is needed to understand biological systems properly. Another key concept is control via feedback regulation. The functional precision of biological systems often relies on feedback regulation. Further, many biological processes (and nanoscale devices) involve small numbers of molecules, and the behavior of such systems is influenced in important ways by stochastic fluctuations. The average response often does not mean much. Biological systems have developed mechanisms to take advantage of stochastic fluctuations as well as to quench their effects, in ways that scientists are just beginning to understand.

Even our understanding of electrostatics and solvation, the underlying forces that govern the action and interaction of charged molecules in polar media, still relies on decades-old approximations or on lessons from necessarily simplified computer simulations. Until all such forces can be accurately computed and combined, scientists will not have a detailed understanding of the action of water and simple ions on intricately constructed macromolecules, much less of the more complex interactions that occur in biological systems.

The recently achieved molecular-level understanding of photosynthetic mechanisms has allowed scientists to create membranes that mimic the essential energy-harnessing properties of natural photosynthesis. A deeper understanding of the structure and function of the photoreaction center of biological systems is inspiring the design of synthetic materials and systems that are even more efficient than those found in nature.

Cellulose is the world’s most abundant biological polymer. Its use as a fuel feedstock to create ethanol is one way to reduce the release of carbon dioxide into the atmosphere, since the carbon dioxide formed during combustion is balanced by that absorbed as ethanol-producing plants grow. Cooperative research exploiting advances in plant genetics, process chemistry, biochemistry, chemical biology, and engineering will make it possible to convert renewable biomaterials like cellulose to useful fuels like ethanol.