Question

What is the permeability (Pm) of a substance whose diffusion coefficient is 3.9 * 10‐9  m2/second and a partition coefficient of 0.6 across a membrane that is 18 nanometers thick? Moreover, what does this information suggest about the polarity of the substance? (2 points)

Answer 1

D 3.9 10m2sec 3.9 10cm2/sec K 0.6 Ar 18nm 18 10m18 10cm Pm-KD 0.6 3.9 10-5 Ar 9 13cm/sec 18 10-7

Polarity of substance does not effect the permeability for inorganic materials. But it does effect in case of polar membranes like cell walls, non-polar molecules does not get effected by the potential of cell membrane and get easily through it. The high polarity(13cm/sec) in our example suggests that, if the membrane is organic like cell membrane, the molecules being permeated are non-polar.