The mechanics of cells: A meeting of mechanics, fluctuations, and geometry

Synopsis

Biology affords us with a number of effectively one- and two-dimensional elastic structures. For example, the cytoskeleton of cells abounds with long stiff protein filaments. Cells are bound by and contain a wide variety of membranes having complex geometries. These lower dimensional structures are typically soft enough so that at room temperature their geometry is strongly fluctuating, and the entropic contribution to their free energy is significant.  In addition, evolution has engineered a plethora of cross-linking proteins and molecular motors that interact with these structures. 

In this talk, I discuss a few examples of the role of fluctuations in these structures, examining the fluctuation-induced (Casimir) interaction between linkers in filament bundles, which can drive a new type of first-order filament bundling transition and type of “line glass” network. I also look effect of geometry on membrane fluctuations, showing how the particular shape of red blood cell membrane localizes their thermal undulations.