Speaker
Description
Exponentially growing cells employ control strategies to maintain a stable size in the presence of noise. Phenomenological models provide important insights into these strategies, revealing classes such as "timer", "adder", and "sizer" control. However, these models necessarily ignore the molecular mechanisms needed to implement the strategy. I will describe our work showing that incorporating these mechanisms can change the model conclusions in important ways. For example, the sizer strategy is thought to minimize the noise in cell size. But using a mechanistic model where division is triggered at a molecular abundance threshold, we find that the adder strategy minimizes noise in cell size. The reason is that cell size noise inherits the molecular noise of the division mechanism. We derive a lower bound on size noise that agrees with publicly available data from six microfluidic studies on Escherichia coli bacteria. Our work connects molecular mechanisms to phenomenological modeling and reveals the consequences of noise propagating across scales.
