BSC 2010 Chapter 7: Chapter 7 Membrane Structure & Function 1
27 Aug 2016
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Selectively permeable (small, hydrophobic molecules (co2, o2) can pass through freely; large, hydrophilic molecules. Two main components: fluid representative of phospholipid bilayer (increases fluidity at warm temperatures, decreases fluidity at cold temperatures, mosaic representative of membrane proteins (allow hydrophilic molecules to enter cell) Nonpolar/small molecules: passively diffuse across the hydrophobic membrane. Polar/large molecules: cannot pass hydrophobic membrane without assistance of membrane proteins: peripheral proteins- bound to one surface of membrane. Integral proteins- embedded in membrane: transmembrane proteins- completely span membrane. Determines blood type rejection by immune system. Passive transport: no membrane required area of low concentration. Diffusion- movement from area of high to. Osmosis- diffusion of h2o across selectively permeable membrane (therefore no energy required for this transport) Structural support (e, f: cell-to-cell or cell-to-ecm adhesion. Transport proteins (a: transports hydrophilic substances across membrane, aquaporin transport protein for moving h2o across membrane, membrane required. Transport proteins allow polar molecules, ions to cross membrane.
