Fig. 1

Schematic of the genetic toggle switch in a growing cell. Schematic shows a replicating bacterial chromosome with the toggle genes inserted in the vicinity of ori (G _ori ) and in the vicinity of ter (G _ter ). For simplicity, for both genes only one inserted copy is shown. As the chromosome is shown during the replication process, G _ori is already replicated while G _ter is not yet replicated. Processes of transcription, gene repression and activation occur with the same rates for both genes. To illustrate gene repression and activation processes the two copies of G _ori are shown in different states. The ‘upper’ copy is in a repressed state with a dimer D _ter bound to the promoter. G _ter and the ‘lower’ copy of G _ori are in an active state