Chapter 23, Problem 51P

The first accurate estimate of cell membrane thickness used a capacitive technique, which determined the capacitance per unit area of cell membrane in a macroscopic suspension of cells; the result was about 1 μF/cm². Assuming a dielectric constant of about 3 for the membrane, find the membrane’s thickness. (Note: Your answer is the thickness of the bipolar lipid layer alone, and is lower by a factor of about 3 than values based on X-ray techniques.)