BIOL 2021 Lecture 5: L5 Chapter 11b
14 Apr 2017
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Mechanism = form a narrow hydrophilic pore. Ions pass in a single file = selective filter. Opens and just stays there so things can just go through fast: energy source. Electrochemical gradient (will always be the source for ion channels) Much faster transport than transporters b/c no conformational change: gating. Figure 11-22: voltage-gated opens when the voltage changes, ligand (anything that binds to something else) gated opens when a molecule binds, can be a nucleotide, protein, neurotransmitter, can be from either side of the membrane, mechanical-gated. Membrane potential opens under mechanical stress: difference in electrical charge across the membrane, measured in units of voltage, plasma membrane in all cells have potential, animal cells: -20 to -120 mv. Negative side: figure 11-23 ionic bases of membrane potential, membrane potential in animal cells. 100mv = 1/100,000 of total k+ in cytosol no significant change in concentration electrogenic causes the potential ex na-k pump: pumps out 3 na, pumps in 2 k.
