BIOL 11000 Lecture Notes - Lecture 5: Facilitated Diffusion, Passive Transport, Active Transport
12 Sep 2016
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Why are lipids not true polymers: they don"t share the same building blocks (monomers) Boundary b/w inside of cell & surroundings. Phospholipid bilayer w/ proteins, other lipids, hybrid molecules. Fluid mosaic model- membrane is mosaic of proteins bobbing in fluid bilayer of phospholipids. Proteins tend to aggregate, not evenly dispersed. Some proteins move, some held in place. Temperature affects fluidity: fluidity decreases as temperature drops, fluidity increases as temperature goes up, too far either way is lethal. Membrane will freeze at some point, depending on molecules: unsaturated fats increase fluidity, saturated fats decrease fluidity. Cells control membrane fluidity to maintain optimum by changing lipid composition. Integral proteins: exist partially in the hydrophobic bilayer interior: transmembrane proteins span membrane (most, other proteins go from one side to interior & stop. Peripheral proteins: not embedded, on one side or the other. Some proteins have more than one function. Membrane protein of one cell recognized by membrane protein of another usually short interactions.
