Fig. 5.

Change in the concentration of inducer or corepressor causes transitions between unimodal and bimodal gene expression. (A) In a noncooperative system, bimodality emerges as the ratio c of TF binding to unbinding rates increases. (B) In a cooperative system, bimodality emerges and then disappears as c increases. Arrows indicate the increase of c. Parameters for A are the same as in Fig. 2A with β₁, and parameters for B are the same as in Fig. 2D with β₁, a = 500, and b = 1.