Physics Dept Seminar

October 1st, Monday

You Are What You Eat:

The Biophysical Consequences of Fat

Prof. Ed Lyman

Univ. of Delaware

(Biophysics, Host: Dias)

*SPECIAL TIME: 1:15pm - 2:15pm with 1pm tea time

Room: ECE 202

The membranes of our cells are made of fat, protein, and sugar. The fat is mainly two-tailed amphiphiles called lipids, which self assemble into bilayers that are a quasi two-dimensional fluid — 4 nm thick, hundreds of square microns in area, and coupled to the bulk solvent inside and outside the cell. Following recent advances in high resolution mass spectrometry, we now know that the membrane contains an enormous variety of different lipids, on the order of hundreds. What are all these lipids for? Is it just a consequence of biological complexity, or must the membrane obtain particular biophysical properties? I will discuss the challenges presented by such a complex and "scale-rich" fluid, motivated by a few key experimental measurements, and our own efforts to address these challenges through a combination of simulation approaches. One approach uses chemically detailed models and a special purpose supercomputing resource to study the thermodynamics of lipid mixtures. A second approach combines molecular dynamics simulation with a mesoscopic method for hydrodynamics to model encounter and signaling in membranes on biologically relevant timescales, where the curiously long-ranged hydrodynamics of membranes yield surprising effects.