ATP and the nonequilibrium wonderland of biology (Chapter 1)

This chapter introduces key principles of nonequilibrium science. Nonequilibrium phenomena are everywhere around us, and inside us, because any system that takes in (or gives off) energy or matter is out of equilibrium. The chapter focuses on the molecule ATP, famously the "fuel" of the biological cell, which gains its capacity to do work not from its chemical structure but from the cell's continual investment of energy to keep ATP out of equilibrium with its hydrolysis products. Using only basic algebra, the chapter illustrates the use of ATP to power what otherwise would be unfavorable cellular processes, including biosynthesis, transport, and signaling. The analogous molecule GTP enables error correction (proofreading) in the synthesis of proteins.