Keeping track of everything without accountants

Biological question:
How do cells organise their myriad ongoing chemical processes and reactants?

Physical ideas:
a. Bilayer membranes self-assemble from their component molecules; the cell uses them to partition itself into separate compartments.
b. Cells use active transport to bring synthesized materials to particular destinations.
c. Biochemcial processes are highly specific . Most are mediated by enzymes, which select one particular target molecule and leave the rest alone.

Nelson, Biological Physics, page 37