Theory of cell size homeostasis

Cells maintain a stable size as they grow and divide. But how they do so in the face of internal and external noise sources has proven to be a surprisingly difficult question to answer. In this talk, I will review the standard models of bacterial cell size control and highlight experimental observations that cannot be explained by these models. In particular, recent evidence from our collaborating group suggests that cell size correlations can last for many generations, rather than one or two as commonly assumed. I will introduce a theory that explains these long-lived correlations and why they may not have been observed before. Furthermore, I will demonstrate that the properties of so-called timer, adder, and sizer models change when intracellular molecule number noise is taken into account. Surprisingly, for example, the sizer model no longer produces the tightest cell size distribution. This work generalizes and advances our understanding of the minimal ingredients needed for stable cell growth.