BIOL 1100 Lecture Notes - Lecture 1: Second Messenger System, Reversal Potential, Farad
30 Jan 2017
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Document Summary
Cell concentrations: concentrations in 100mm range for the ions. Diffusion: small, non-polar, uncharged, lipophilic substances are able to pass through lipid bilayer, some small polar molecules (water) Ion channels: allow small charged molecules to pass through and takes water with it. Ions actually pass through faster than diffusion: selectivity filter. Narrow region of the channel"s pore where the choice is made which ion will go through. Depends on size of ion, size of hydrated ion, net charge, charge density, dehydration e (how easy it is to strip off the water molecules solvating the ion: gating. Ligand-gated: when ligand binds, goes from closed to open conformation and allows ion to go through. Some ligands are ec (neurotransmitters, hormones), some are ic (g-protein, Voltage-gated: change in voltage opens the channel (most by positive voltage) Particularly important in nerve impulses, muscle contraction (very rapid) Direction of ion flow depends on electrochemical gradient. Some respond to hot temperatures and also respond to capsaicin.
