A Special Joint Seminar with Complex Systems and Biophysics.

Abstract:
Biological systems are immensely complicated at the molecular scale. However, their macroscopic behavior is rich, but often comprehensible. I will first present a geometric framework for quantifying this emergent simplicity, highlighting parallels with continuum limits in physics. I will then focus in on the plasma membrane, a two dimensional liquid that surrounds mammalian cells. Recent experiments have demonstrated that this membrane is close to a liquid-liquid critical point, distinguished by emergent time and length scales much larger than individual molecules. We have recently shown that anesthetics take membranes away from criticality while anesthetic reversers restore criticality. Membrane criticality has profound implications for ion channels, mediating long-ranged forces, sensitive allosteric regulation and non-Markovian dynamics. This has led us to hypothesize that anesthetics influence ion channel function by disrupting the critical membrane.