Dresden 2011 – scientific programme
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BP: Fachverband Biologische Physik
BP 7: Posters: Statistical Physics in Biological Systems
BP 7.16: Poster
Monday, March 14, 2011, 17:15–20:00, P3
Investigating intrinsic fluctuations in biochemical systems — •Joseph Challenger1, Juergen Pahle2, Alan McKane1, and Pedro Mendes2 — 1School of Physics and Astronomy, The University of Manchester, Manchester, UK — 2School of Computer Science, The University of Manchester, Manchester, UK
Mathematical models of biochemical reaction systems are usually constructed from determinstic rate equations. However, this approach is not appropriate when the number of molecules involved is low. Here the underlying stochasticity present in the system becomes important.
The rate equations treat the molecular concentrations as smoothly varying functions. In this talk, a master equation approach is used, where the system is described by discrete states, namely the molecular populations of the chemical species involved. In the mean field limit the rate equations can be recovered. In addition to this, leading order corrections to the rate equations can be obtained by using the system-size expansion due to van Kampen.
We have incorporated these results into COPASI, a software package designed to simulate and study biochemical reaction systems. This allows the expansion procedure to be automated. Once the reaction system has been described, COPASI can calculate the covariance matrix associated with the fluctuations exhibited by the chemical species present in the system. We give examples of the application of the method to biologically relevant systems.