FIGURE 7.

Elementary modes (A) and minimal generating set (B) for the example model displayed in Fig. 1 with J₂, J₃, and J₄ as reversible, and J₁, J₅, and J₆ as irreversible reactions. The modes EM₁ and GM₁ are reversible; thus, the wedge is open in the positive and the negative J₄ directions. The reversible cycles do not operate by themselves; they must be coupled to an input output mode. This leads to two additional inequalities (see text). The resulting flux-cone is pointed, revealing a pyramidal shape (C).