Fig. 3.

Bi-stable genetic switch. The genetic switch idea was first proposed by M. Delbruck. Perhaps due to the brevity of his comment, or the obviousness (to him) of such an idea, M. Delbruck did not draw a bi-stable landscape. The landscape here is instead for phage lambda genetic switch, taken from Zhu et al. (2004). The regimes with dense equal potential lines are two attractive basins, the viable two stable states. The coordinates are the numbers of two proteins controlling the switch. It appears to be the first quantitative construction of such a landscape for genetic switch based on physics, chemistry, and biology principles (from Zhu et al., 2004).