About
sixty years ago, Gorter and Grendel estimated that erythrocytes contain
sufficient lipid to form a bimolecular lipid plasma membrane. With
the benefits of more modern techniques we now know these pioneers made two
errors in their measurements:
- Their lipid extraction procedures ( with acetone) removes only about
75% of RBC lipid. More stringent extraction—using chloroform
and methanol—removes 100% of the lipid.
- Their estimates of RBC surface area were made on stained blood smears
(a thin, stained film of dried blood) and yielded an average value of
99.4 µ2 per cell. More recent measurements using
Nomarski differential interference microscopy and living cells suspended
in serum indicate a surface area of 138 ± 17.3 µ2.
a. (8 pts) How did Gorter and Grendel reach their conclusions.
What sorts of measurements did they perform and how did the results lead
to their conclusion?
b. (5 pts) Assuming the recent determinations are more valid, how
might the original inference of Gorter and Grendel be critically re-evaluated?
Be specific.
c. (8 pts) Do the new data provide any additional information concerning
our modern view of plasma membrane organization? Support your answer
with a brief discussion.
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