BIOL 112 Lecture Notes - Lecture 3: Hemoglobin, Semipermeable Membrane, Cell Membrane
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BIOL 112 Full Course Notes
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Document Summary
A cell"s membrane fluid mosaic comprised of phospholipid bilayer, membrane- associated proteins, and other things. Formation of phospholipid bilayer is thermodynamically favourable, influenced by non-covalent interactions within phospholipids, but primarily by entropy of water. Factors that determine what passes through phospholipid bilayer: Molecular size smaller things pass through membrane easily. Polarity non polar molecules pass through membrane easily. Na+ ion can"t get through lipid bilayer because water from a hydration shell around an-ion through ion-pd bonds and won"t let it pass. Carbon pulled equally in each direction so not polar. Diffusion movement of substance from high concentration to a low concentration until equilibrium is reached (no net movement). Size (smaller molecules get through easily) & permeability (holes of membrane) Facilitated diffusion requires membrane proteins, move along concentration gradient, can move in two directions. (*no energy). Allows larger or more polar molecules through along concentration gradient. Transmembrane proteins: transport, enzyme, signal, cell recognition.
