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Article: Membrane Transport
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- Biology
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CopyrightCOPYRIGHT 2002 The Gale Group Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Membrane Transport
Biological membranes are the structures that divide biological space into functional
aqueous
compartments: cells and their
organelles
. To allocate hundreds of different
solutes
to their proper locations, cells equip their various membranes with multiple transport mechanisms, some simple and some complex. (Use of membrane
vesicles
for endocytosis and exocytosis is covered elsewhere.)
Membrane Diffusion
The simplest kind of transport is the unassisted diffusion of solutes across membranes (see Figure 1a). The kinds of molecules that transit in this fashion are more soluble in oil than water and so readily dissolve in and then spontaneously traverse the ...