Chromosome, Cell Cycle and Entropy (or: why I love E. coli)

RLM 11.204
Suckjoon Jun
Harvard University
Chromosome, Cell Cycle and Entropy (or: why I love E. coli)

Before an Escherichia coli cell divides to give two viable daughter cells, the constantly growing cell must replicate, topologically decatenate, and spatially segregate its genetic materials. These processes pose non-trivial, conceptual questions at the interface between physics and biology. In this talk, I will discuss the questions in two independent and yet related contexts. In the first part, I will focus on the spatial processes involving chromosomes, and present experimental and theoretical results to show that the bacterial chromosome behaves as a loaded entropic spring, strongly confined by a crowded environment inside the cell. The second part concerns temporal processes the cell must coordinate, and I will show that E. coli possess a very robust mechanism of growth. I will conclude with one of the long-standing questions in biology, which we physicists may view as a “causality” problem.