Lectures 11-12 Membrane strucure and transport

Lectures 11-12 Membrane strucure and transport - Recall...

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Diagram of a lipid bilayer formed by phospholipid molecules in an aqueous environment Hydrophilic head Hydrophobic tail WATER WATER Recall from the lecture on lipids—biomembranes are a phospholipid bilayer
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Cell membranes is fluid because of unsaturated fatty acids and…
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…cholesterol
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The fluid mosaic model for membranes Membrane proteins are embedded in the fluid lipid and free to diffuse in two dimensions but not to enter and leave the membrane
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The detailed structure of an animal cell’s plasma membrane, in a cutaway view Although membranes appear to be complex they can be broken down into two major components, proteins and lipids, that divide up the functions of the membrane
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Membrane components and their functions: 1. Lipids – function primarily as a sealant that keeps what’s outside out and what’s inside in 2. Proteins—two main types, integral (embedded in the lipid bilayer) and peripheral (loosely attached to the surface, ususally to another integral protein. 3. Proteins play two major roles a. selective import and export through the bilayer b. communication (cell signaling)
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Integral membrane proteins have three “domains” (regions) Extracellular Transmembrane Intracellular EXTRACELLULAR SIDE N-terminus C-terminus α Helix CYTOPLASMIC SIDE
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We will focus on two functions : 1. Transport – how molecules cross the lipid bilayer 2. Signaling – how information crosses the lipid bilayer Common theme: lipids form a barrier, proteins allow for passage
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This note was uploaded on 11/14/2011 for the course BSC 2010 taught by Professor Pf during the Spring '08 term at FSU.

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Lectures 11-12 Membrane strucure and transport - Recall...

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