Biology 1002B Lecture Notes - Lecture 2: Lipid Bilayer, Fluid Mosaic Model, Membrane Fluidity
28 Feb 2016
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Document Summary
Material covered membrane structure, passive transport, active. Membranes are composed of a selectively permeable phospholipid bilayer. Proteins embedded or attached to the membrane perform membrane functions. Hydrophobic (water fearing)- associate with each other away from water. Assembly of bilayer is spontaneous in an aqueous environment. Structure is favored (low energy state: hydrophobic fatty acid chains minimize water contact by aligning in the core, polar heads interact with water. Proteins embedded or bound to the membrane can also move laterally. Human and mouse cells grown separately in tissue culture. Human and mouse membrane proteins tagged with different dye molecules. Although fluid, cell structure is maintained by membrane protein attachment to cytoskeleton: human-red, mouse-green, proteins mixed. Membrane fluidity influenced by: fatty acid saturation and temperature. As temperature drops the random motion of lipids slows down: fluidity lost at certain point gelling point, more unsaturated molecules will have a lower gelling point of the membrane (why?)
