BIOL 111 Lecture Notes - Lecture 9: Alpha Helix, Lipid Bilayer, Signal Transduction
31 Jul 2016
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Document Summary
Facilitated diffusion: transport protein speed the movement of molecules. Integral proteins: penetrate thenhydrophobic core of the lipid bilayer. Multiple amphipathic alpha helices can associate to form a hydrophilic pore. Peripheral proteins: are appendages loosely bound to the surface of the membrane. Functions of membrane proteins- transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to the cytoskeleton and extracellular matrix. Membrane carbohydrates- interact with the surface molecules of other cells, facilitating cell-cell recognition. Aquapourins (water channels) allow for the bulk transport of wter across the hydrophobic plasma membrane. Carrier proteins- undergo a subtle change in shape that translocates the solute binding site across the membrane. Sodium potassium pump- type of active transport system. Animal cell has higher concentrations of potassium and lower concentrations of sodium outside of the cell. An electrochemical gradient- caused by the concentration/electrical gradient of ions across the membrane. Electrogenic pumps- a transport that generates the voltage across a membrane.
