DNA unzipping and motor proteins: Effect of the genetic code

About:

The past decade has witnessed a revolution in polymer science and biophysics, as scientists use exquisitely sensitive tools such as laser tweezers, novel linking agents and magnetic micro-beads to probe polymeric ingredients of the "central dogma" of biology, such as DNA and RNA, one molecule at a time. We discuss the role played by entropic elasticity, and describe experiments with force-induced unzipping of DNA. Flexible polymerized or "tethered" membranes, which are natural generalizations of these linear polymer chains, are treated next. We again turn to biology, and discuss the spectrin skeleton of red blood cells. Theory predicts a remarkable flat phase, with anomalous roughness and singular elastic constants, caused by a delicate interplay between thermal fluctuations and the Gaussian curvature.

Short biography:

Professor David Nelson, born in 1951, studied physics at Cornell University and obtained his PhD from Cornell University in 1975. He became full professor of physics at Harvard University in 1980. He was appointed Mallinckrodt professor of physics in 1992 and professor for applied physics in 1997, both at Harvard University.

David Nelson's research focuses on collective effects in the physics and chemistry of condensed matter. He has been interested, in particular, in the interplay between fluctuations, geometry and statistical mechanics. In collaboration with his Harvard colleague, Bertrand I. Halperin, he is responsible for a theory of dislocation-mediated melting in two dimensions. David Nelson's research includes a theory of the structure and statistical mechanics of metallic glasses and investigations of "tethered surfaces", which are two-dimensional generalizations of linear polymer chains. He has also studied the flux line entanglement in the new, high temperature superconductors. His current interests include vortex physics, the statistical mechanics of polymers, topological defects on frozen topographies and biophysics.

David Nelson's achievements have earned him numerous prestigious awards, including the Bardeen Prize (2003) for his research in superconductivity, and the Buckley Prize (2004) for his seminal contributions to soft condensed matter physics. He was elected to the National Academy of Sciences (USA) in 1994.