BIOL 102 Lecture Notes - Lecture 12: Lipid Bilayer, Facilitated Diffusion, Passive Transport
29 Aug 2016
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Document Summary
Permeability is the movement of ions/molecules across a membrane. Ions & hydrophilic molecules hard to pass. Diffusion: solute moves from high low concentration: passive diffusion no transport protein nneded. Rate depends on chemical properties/concentration of solute. Permeability from high to low: gases, small/uncharged molecules, water, urea, polar organic molecules (ex: glucose) Gradient: transmembrane gradient: concentration of solute is higher on one side of the membrane thant the other. Controled through passive transport: no input of energy. Diffusion of solute through phospholipid bilayer to move across membrane. Facilitate movement of various nutrients across membrane (aid of transport proteins) Osmosis: osmosis: movement of water across membranes in response to solute concentration gradients. Water passively moves where the solute concentration is higher: osmotic pressure: hydrostatic pressure needed to stop net flow of water across membranes due to osmosis. Plants, cell wall pushes against the wall internal water pressure; tugar pressure. Prevents further entry of water: tonicity: effects of surrounding solution on cell volume.
