Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 4

Gorter and Grendel Revisited. Gorter and Grendels classic conclusion that the plasma membrane of the human erythrocyte consists of a lipid bilayer was based on the following observations: (i)the lipids that they extracted with acetone from 4.74 × 10 9 erythrocytes formed a monolayer 0.89 m 2 in area when spread out on a water surface; and (ii)the surface area of one erythrocyte was about 100 m 2 , according to their measurements.
(a)Show from these data how they came to the conclusion that the erythrocyte membrane is a bilayer.
(b)We now know that the surface area of a human erythrocyte is about 145 m 2. Explain how Gorter and Grendel could have come to the right conclusion when one of their measurements was only about two-thirds of the correct value.