Figure 1

A simple switch. Regulatory switch network (A) and the reaction networks belonging to its three consistent organizations (B, C, and D). Absent species appear in gray. Inactive reactions and interactions are dashed. Panel B represents Organization 10 = {A, I} where inhibitor I represses both reactions from A to P 1 and P 2. Panels C and D represent Organization 11 = {A, P 1} and Organization 12 = {A, P 2} where one pathway is active, either over P1 or P2.