Current-noise recordings from a membrane patch containing identical

PHYSICS · Subjective · Fermi University Physics · Scientific Practice & Experimental Methods · Biophysics & Medical Physics · Molecular machines, transport and bioenergetics

Forces, Machines and Signals, Ch Channels, pumps and the resting potential

Problem

Current-noise recordings from a membrane patch containing NN identical, independent channels each of unitary current ii give a variance σ2=iIˉ−Iˉ2/N\sigma^2 = i\bar I - \bar I^2/N, where Iˉ\bar I is the mean current. Two points on the variance-mean curve are measured. Data: Iˉ=22.5 pA\bar I=22.5\,\mathrm{pA}, σ2=30.4 pA2\sigma^2=30.4\,\mathrm{pA^2}; Iˉ=157.5 pA\bar I=157.5\,\mathrm{pA}, σ2=70.9 pA2\sigma^2=70.9\,\mathrm{pA^2}. Find the unitary current ii and the channel number NN.

Browse the problem library