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Applied Math Colloquium

Friday, January 24th, 2014, 11:30 AM
Cullimore Lecture Hall, Lecture Hall II
New Jersey Institute of Technology

Role of thermal fluctuations in supercoiled DNA and filament networks

Prashant Purohit

University of Pennsylvania

Abstract

In this talk we will discuss two problems within the general framework of entropic elasticity and biophysics. The first problem concerns supercoiled DNA where we show that bending, twisting, electrostatics and entropy due to thermal motion have to be carefully considered to quantitatively account for the results of single molecule experiments. We are able to capture all the details of the extension-rotation curves obtained in DNA twisting experiments for various concentrations and types of ionic solutions. The second problem concerns filament networks where we show how the quasi-harmonic approximation of statistical mechanics can be combined with the finite element method to understand the importance of fluctuations in semi-flexible filament networks. This technique enables us to capture strain stiffening as well as softening due to filament buckling in networks of actin filaments.