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Active gels and snake-like chains: Two stories of biomolecular mechanics

Seminar Group: 


Prof. Omar Saleh


Associate Professor, Materials
Biomolecular Science and Engineering Program, UCSB


Friday, November 2, 2012 - 4:00pm


ESB 1001


Prof. Ed Kramer

Soft biomolecular systems display a range of interesting mechanical properties, including both the active, non-equilibrium behaviors characteristic of living things, and the passive, entropic responses that arise from their flexible polymeric constituents. Our group investigates various aspects of biomolecular mechanics, and I'll describe two of our projects in detail.

First, we are inspired by the active mechanics of living cells, which arises from the action of motor proteins that create stresses within the cell's pervading gel, the cytoskeletal network. As a first step towards creating artificial materials with cell-like properties, we have synthesized a DNA gel that, upon activation of bound DNA-based motor proteins, displays mechanical fluctuations quantitatively equivalent to those of the cytoskeleton.

Second, while certain biomolecules generate force, others respond to applied force in interesting ways. In particular, I will argue that the elastic response of single polymers is a powerful way to investigate polymer structure. As an example of this, I will show how a variety of observations have led us to conclude that single-stranded DNA conformation cannot be described through the classical worm-like chain picture, but rather has a 'snake-like' conformation with a unique short-range, crumpled structure that is likely characteristic of all flexible polyelectrolytes.