BIOL 2021 Chapter 10: Membrane Structure
1 Feb 2017
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Document Summary
The plasma membrane encloses the cell, defines its boundaries, and maintains the essential differences bw the cytosol and the extracellular environment. All biological membranes have a common general structure: each is a very thin film of lipid and protein molecules, held together mainly by noncovalent interactions. Cell membranes are : dynamic, fluid, their molecules move in the plane of the membrane, the lipid molecules are a double layer about 5nm thick. The lipid bilayer provides the basic fluid structure of the membrane and is an impermeable barrier to the passage of most water soluble molecules. Phosphoglycerides, sphingolipids, and sterols are the major lipids in cell membrane. All lipid molecules in cell membranes are amphiphilic they have a hydrophilic (water loving, polar) end and a hydrophobic (water hating, nonpolar) end. Most membrane lipids are the phospholipids: have a polar head group that has a phosphate group, and have two hydrophobic hydrocarbon tails.
