lecture02 - LECTURE 2. 26 August 2009 (P. Hollenbeck) BIOL...

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LECTURE 2. 26 August 2009 (P. Hollenbeck) BIOL 231 Note figs 1-19 thru 1-25 and panel 1-2; see DVD 15.11; work Problems: 3-7 I. 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 (plasma membrane) defines the cell! For eukaryotic cells, the boundaries between organelles and 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 – we will return to this soon, in some detail. (2) Contains ORIENTATED proteins & amphipathic lipids; very little "flipping" of lipids between leaflets; virtually no switching of orientation of transmembrane proteins; THEREFORE the two sides of a membrane are different! (1) Continuous: makes it a real boundary! (2) Selectively Permeable: prevents free diffusion but allows or manages exchange (3) Asymmetric: inside diff than outside; lipids, proteins, carbohydrates
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This note was uploaded on 12/18/2009 for the course BIOL 101 taught by Professor Wormer during the Fall '08 term at Purdue University-West Lafayette.

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lecture02 - LECTURE 2. 26 August 2009 (P. Hollenbeck) BIOL...

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