lec2 note - -1-LECTURE 2. 25 August 2010 (P....

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Unformatted text preview: -1-LECTURE 2. 25 August 2010 (P. Hollenbeck)BIOL 231TOPOLOGY OF CELLS, MEMBRANES & ORGANELLESNote figs 1-19 thru 1-25 and panel 1-2; see DVD 15.11; work Problems: 3-7I. Organizational principles(A) General properties of ordered systems(1) order implies a BOUNDARY between the system and the outside world, and energy expenditure at the boundary (to overcome entropy)(2) Note that the boundary between the cell and the outside world (plasmamembrane) defines the cell! For eukaryotic cells, the boundaries between organellesand the cytoplasm are absolutely critical for most specialized cell functions.(B) The Bilayer(briefly)(1) Comprised of two lipid leaflets, each with polar head groups facing water wewill return to this soon, in some detail.(2) Contains ORIENTATED proteins & amphipathic lipids; very little "flipping" oflipids between leaflets; virtually no switching of orientation of transmembraneproteins; THEREFORE the two sides of a membrane are different!(C) 7 Principles of membrane structure & function(1) Continuous: makes it a real boundary!(2) Selectively Permeable: prevents free diffusionbut allows or manages exchange (3) Asymmetric: inside diff than outside; lipids,proteins, carbohydrates (4) Disequilibrium: ELECTRICAL &...
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lec2 note - -1-LECTURE 2. 25 August 2010 (P....

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