Fig. 1

Cells maintain a relatively higher degree of order compared with their environment by continually importing free energy in the form of nutrients and exporting entropy as disordered wastes and heat. Cells selectively import ordered nutrients from a largely chaotic world via its semipermeable cell membrane, composed of substrate-specific protein channels and transporters (colored cylinders) embedded in a relatively impermeable phospholipid (dotted lines) membrane. A cell’s metabolism converts nutrients into usable forms of energy (ATP) and into diverse biomolecules that are used for self-maintenance, reproduction, and growth. The costs of converting nutrients into these useful low entropy forms for self-preservation are the production of high entropy wastes and heat. The constant export of entropy from cells via the cell membrane ensures the cells maintain higher internal order compared with their external environment