Question

Cell membranes (the walled enclosure around a cell) are typically about d = 7.0 nm thick. They are partially permeable to allow charged material to pass in and out, as needed. Equal but opposite charge densities build up on the inside and outside faces of such a membrane, and these charges prevent additional charges from passing through the cell wall. We can model a cell membrane as a parallel-plate capacitor, with the membrane itself containing proteins embedded in an organic material to give the membrane a dielectric constant of about 17.

a) What is the capacitance per square centimeter of such a cell wall? Ans: c = ___ μF/cm2

b) In its normal resting state, a cell has a potential difference of 85 mV across its membrane. What is the electric field inside this membrane? Ans: E = ___ V/m

Answer 1