At extremely low concentrations, the number of molecules that can participate in a chemical reaction becomes so small that fluctuations (noise) about the mean concentration start to become important. The transcription factor protein (the 'lac repressor') which controls the genes associated with lactose metabolism in E. coli provides a well known example. The lac repressor is active at nanomolar concentrations, for which one can compute there are only of the order ten molecules present in an E. coli cell volume. To understand the effects of fluctuations in biochemical reaction networks, one can solve for the properties of a selection of linear reaction networks (linear networks do not involve bimolecular reactions). The analysis sheds light on how noise is transmitted through detection motifs, and how to 'coarse-grain' reaction networks by the elimination of fast reactions.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..