An actin filament can be modelled as a solid rod of radius (diameter about )

PHYSICS · Multi-part · Fermi University Physics · Biophysics & Medical Physics · Macromolecules, membranes and cell architecture · Macromolecules, membranes and cell architecture

Forces, Machines and Signals, Ch Filaments, networks and the mechanics of whole cells

Problem

An actin filament can be modelled as a solid rod of radius

3.5\,\mathrm{nm}

(diameter about

7\,\mathrm{nm}

). Thermal shape analysis gives its persistence length as

\xi_p = 17\,\mathrm{\mu m}

T = 298\,\mathrm{K}

. ((a)) Find the bending rigidity

\kappa = k_BT\xi_p

. ((b)) Find the second moment of area

I = \pi r^4/4

of the rod. ((c)) Find the effective Young's modulus

E = \kappa/I

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