Short Stories in Soft Condensed Matter of How Complex Behavior in Membrane Systems Arises from Minimal Components

Condensed Matter Seminars

Speaker: Sarah Keller, University of Washington
Date & Time: November 26, 2015, 2:00 - 3:00
Location: Hennings 318
Local Contact: George Sawatzky
Intended Audience: Graduate

This talk will briefly summarize our laboratory’s recent condensed matter research inspired by biological questions. Asking how sub-micron composition fluctuations might arise in a lipid membrane near a critical point led to our determination of the membrane’s effective critical dynamic exponent — the first successful systematic measurement of this fundamental physical parameter in any 2-dimensional Ising system with conserved order parameter, whether biological or not (Honerkamp-Smith et al. PRL 2012). Far from the critical point, the membrane demixes into coexisting liquid phases. Asking how groups of lipids diffuse within a membrane led to our measurement of growth exponents for membrane domains (Stanich et al. 2013). Asking whether tension in a membrane can make those domains appear or disappear led to our quantification of how tension changes miscibility temperatures (Portet et al. BJ 2012). Last, simply for fun, asking how molecules on the early Earth assemble into protocells of RNA surrounded by a membrane led to our discovery that the building blocks of RNA (nucleobases and sugars) bind to fatty-acid membranes and enhance the membrane’s stability (Black et al. PNAS 2013). These interactions could have plausibly contributed to the emergence of the first protocells on the early Earth (and eventually to physicists and chemists).