Which scientist proposed the Unit Membrane Model?
Early electron microscopy after osmium fixation revealed trilaminar image of membranes about 7.5 nm thick: two dark lines 2 nm each representing protein stained by osmium, light core of lipid. J. David Robertson at Harvard analyzed myelin, chloroplast, and plasma membranes and in 1959 proposed Unit Membrane Model asserting all biological membranes share same basic construction of lipid bilayer sandwiched between non-lipid layers, with asymmetry that inner and outer surfaces differ chemically, explaining functional polarity. Robertson emphasized continuity of membranes through ER and nuclear en
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 10: Unit Membrane Model, Robertson.
