A patch of phospholipid bilayer has area expansion modulus and ruptures (lyses) at a…

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

Forces, Machines and Signals, Ch The fluid membrane: bending, flicker and shape

Problem

A patch of phospholipid bilayer has area expansion modulus

K_A = 0.20\,\mathrm{N\,m^{-1}}

and ruptures (lyses) at a tension

\sigma_{\rm lys} = 6.0\,\mathrm{mN\,m^{-1}}

. A micropipette holds the patch at a working tension of

\sigma = 3.0\,\mathrm{mN\,m^{-1}}

, small enough that the area strain is Hookean,

\sigma = K_A\alpha

with

\alpha = \Delta A/A

. ((a)) Find the area strain

\alpha

at the working tension. ((b)) Find the area strain at which the patch would lyse. ((c)) In one sentence, explain how a cell can change its volume by tens of per cent during swelling even though its membrane tears at only a few per cent area strain.

Browse the problem library