Role of Communication
Aside from acting as a physical barrier to the loss of system order, the membrane also acts as a vital communication link between its inside and outside. Maintaining the system order requires that it be robust to a wide range of environmental perturbations. This requires information to serve as a memory or template of the fundamental state of the system (as, e.g., B cells preserve a memory of past pathogens so as to more quickly suppress them when they reappear). As order is lost due to normal cell functions, the system must continuously act to restore it, i.e., restore the primary state.
How did the cell "learn" that it was required to restore the primary state ?
1. Cellular Origin, Life in Extreme Habitats and Astrobiology Volume 22