BSCI 426 BIOL 622    Fall '14 Problem Set 5

assigned:     10/02/14
due:            10/09/14

When one drinks an alcoholic beverage such as beer or wine, the ethanol gets into our blood stream quite rapidly yet the intestinal epithelium has no transport systems for ethanol.

1. How does it cross the plasma membrane of the epithelial cells?

2. Estimate the permeability of the epithelial plasma membrane for ethanol.

3. Estimate the unidirectional flux of ethanol through the plasma membrane of the epithelial cell if the solution in the lumen of the intestinal track is beer containing 1 Molar ethanol.

4. Calculate the Stokes/Einstein radius of ethanol.

5. Estimate the permeability of the epithelial plasma membrane for butanol.

6. Calculate the Stokes/Einstein radius of butanol.

7. Which alcohol has a larger size? Which is more permeant? Why?

  Information: For structures check Wikipedia

Diffusion constants: Ethanol: 1.24x10^-5 cm²sec^-1; Butanol: 9.3x10^-6 cm²sec^-1

Oil/water partition coefficients: Ethanol: 0.5; Butanol: 7.4

For the viscosity η (eta), you can use the viscosity of water: 0.01 Poise (P).

1 Poise is 1 g cm^-1 sec^-1

1 Poise = 0.1 Pascal sec