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TOPIC 6: LIPIDS AND MEMBRANES THREE FUNDAMENTAL PROPOSITIONS A lipid bilayer provides the structural backbone and barrier functions of all biological membranes The lipid bilayer is a two-dimensional 'fluid' consisting primarily of phospholipids and glycolipids, and in animal cells, cholesterol The hydrophobic nature of the core of the unit membrane necessitates the presence of proteins to provide, among other things, for the movement of many things across the membrane I suggest you start by reading pp. 23 - 25, 66 - 70; 81 - 82, Ch. 7 pp. 154 - 171. In this lecture we begin to explore cell membranes. Note the functions of cell membranes, that cell membranes have both similar and different functions, and that the different functions are associated with structural (biochemical) specialization. We then look at the history and basic nature of the Unit Membrane. To understand this section you must study the material on lipid chemistry paying particular attention to the concept of hydrophobic interactions and the amphipathic nature of phospholipids. The lipid bilayer, by itself, is about 7- 8 nm thick, each single leaflet is about 3 - 4 nm thick (p. 24) (nice 'ballpark' figures to remember). The lipid biayer is called 'THE UNIT MEMBRANE' . This is the structural backbone of all biological membranes . You must understand the unit membrane very well because the nature of this structure imparts the characteristic of impermeability, imposes the requirements for associated proteins, and explains
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This note was uploaded on 08/06/2008 for the course BIO 1140 taught by Professor Fenwick during the Winter '07 term at University of Ottawa.

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