Professor David Nelson
Lyman Laboratory of Physics
Harvard University
Cambridge, MA

Tuesday, January 21, 2003
3:00 pm (CT)
3269 Beckman Institute

Abstract

Localized and extended states play important roles in a number of biological problems. We discuss in some detail the delocalization in DNA when the two strands are pulled apart by a constant force. When the force exceeds a critical threshold, a remarkable unzipping transition occurs which is strongly influenced by randomness in the base pair sequence. The DNA unzips via a series of discrete jumps which allow it to reach successively deeper energy minima. This remarkable behavior has recently been seen in experiments on lambda phage DNA by the Prentiss group at Harvard. Above the threshold force, the dynamics of the unzipping force is related to that of a particle diffusing in a random force field. Time permitting, we will describe related problems involving the stalling out of detachable motor proteins, such as DNA and RNA polymerase, while moving along linear filaments with quenched randomness.

Tea and coffee will be served in R3151 Beckman Institute at 2:15pm.