This model takes the form of a network of chemical reactions that simulate intracellular processes at the population level. Although the same processes seem anything but deterministic upon a closer look at the single cell, the individual variations can be assumed to be independent and identically distributed for each cell and their averaging eliminates the variability at the population level. Consequently, these chemical reactions are simulated as ordinary differential equations.

The centerpiece is AHL. AHL is the small, freely-diffusing molecule that mediates cell-to-cell communication: when AHL levels are low, the quorum sensing switch is turned off; when they’re high, the switch is turned on. The rest of the interactions concern the protein LuxI, which produces AHL, and LuxR, which binds it and then, activated, goes on to induce the “DNA”. The “DNA” species refers to plasmids carrying the Lux regulatory system. Its induction by (LuxR.AHL)₂ marks the off->on transition; when most of the DNA is in the (uninduced) “DNA’ form, the switch is off; when most of it is in the “DNA.(LuxR.AHL)₂” form, the switch is on.