  In living systems, collective molecular behavior is driven by thermodynamic
forces in the form of chemical gradients. Leveraging recent advances in the
field of nonequilibrium physics, I show that increasing the thermodynamic force
alone can induce qualitatively new behavior. To demonstrate this principle,
general equations governing kinetic proofreading and microtubule assembly are
derived. These equations show that new capabilities, including catalytic
regulation of steady-state behavior and exponential enhancement of molecular
discrimination, are only possible if the system is driven sufficiently far from
equilibrium, and can emerge sharply at a threshold force. Regardless of design
parameters, these results reveal that the thermodynamic force sets fundamental
performance limits on tuning sensitivity, error, and waste. Experimental data
show that these biomolecular processes operate at the limits allowed by theory.
