Dynamic Organization of Biological Cells

Living matter is highly dynamic and organizes in complex patterns and spatial structures. Cells and tissues are driven far from thermodynamic equilibrium by a supply of chemical energy via metabolic processes. I will discuss how active processes drive cells away from thermodynamic equilibrium and I will present general concepts from irreversible thermodynamics that capture the physics of active processes. Fluid flows generated by material contraction driven by active mechanical stresses provide a general mechanism for cell polarity establishment. Phase separated droplets form small compartments in cells that organize biochemistry. Such biological condensates motivate the physical study of chemically active droplets that exhibit nonequilibrium states and that can imitate cell like behaviors such as spontaneous division. Active droplets can also serve as simple physical models of protocells that operate away from equilibrium. Finally, at larger scales, many cells organize collectively during the morphogenesis of organisms. These examples show that living matter is a form of active matter governed by nonequilibrium physics. To advance our understanding of principles that underlie the emergence of complex biological structures far form thermodynamic equilibrium will remain a challenge for future research.