Genetic Toggle Switch
This Demonstration implements a mathematical model of the "genetic toggle switch" gene network. The genetic toggle switch consists of two genes, each of which encodes for a protein that represses the other's gene expression. Because of the even number of components in the circuit, there is a net positive feedback, which can give rise to bistable behavior for certain parameter values. The behavior of each repressor concentration is visualized as a function of time.
The genetic toggle switch was described and implemented in E. coli in .
 T. S. Gardner, C. R. Cantor, and J. J. Collins, "Construction of a Genetic Toggle Switch in Escherichia coli," Nature, 403, 2000 pp. 339–342.