Bistability: Difference between revisions
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Characteristic of the system to respond to stimulus in a non linear fashion, contribute to a "all or none" behavior. Ultrasensitivity can arise by multiple ways, including cooperativity. It account for the emergence of threshold levels of activation of a given transition. | Characteristic of the system to respond to stimulus in a non linear fashion, contribute to a "all or none" behavior. Ultrasensitivity can arise by multiple ways, including cooperativity. It account for the emergence of threshold levels of activation of a given transition. | ||
*'''Hysteresis''' | *'''Hysteresis''' | ||
History dependent behavior, kind of memory [http://en.wikipedia.org/wiki/Hysteresis#Cell_biologysee also here]. An example of thermal hysteresis is the melting of agarose: you need to heat it at 100°C to liquefy it, but to maintain it at only 60°C to keep it liquid. | |||
In biology, key example include the lactose operon, or the activation of cdc2-cyclinB1. In both case the system requires less stimulus to maintain the state than for switching to this state. The refractory period in neuron stimulation is also a good example [http://en.wikipedia.org/wiki/Refractory_period_(physiology) see here]. | In biology, key example include the lactose operon, or the activation of cdc2-cyclinB1. In both case the system requires less stimulus to maintain the state than for switching to this state. The refractory period in neuron stimulation is also a good example [http://en.wikipedia.org/wiki/Refractory_period_(physiology) see here]. | ||
Revision as of 21:34, 17 December 2008
Bistability is a particular case of multistability, the property of a system to reside in different stable steady-states without being able to rest in intermediate states [1].
Properties of bistable systems
- Feedback
Often, bistable states are maintained by the help of positive feedback, negative feedback on the other sate players, self-catalysis.First decribed by Monod and Jacob in 1961 [2]. Often found in combination.
- Ultrasensitivity
Characteristic of the system to respond to stimulus in a non linear fashion, contribute to a "all or none" behavior. Ultrasensitivity can arise by multiple ways, including cooperativity. It account for the emergence of threshold levels of activation of a given transition.
- Hysteresis
History dependent behavior, kind of memory also here. An example of thermal hysteresis is the melting of agarose: you need to heat it at 100°C to liquefy it, but to maintain it at only 60°C to keep it liquid. In biology, key example include the lactose operon, or the activation of cdc2-cyclinB1. In both case the system requires less stimulus to maintain the state than for switching to this state. The refractory period in neuron stimulation is also a good example see here.
