Lecture 14 Active Transport then Membrane Potentials

Lecture 14 Active Transport then Membrane Potentials -...

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Lecture 14 Active Transport ATP used as energy source Na + , K + ATPase H + , K + ATPase Other energy sources Light Secondary Active transport Membrane Potentials Nernst equation
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Main Points In active transport, energy is needed to move solutes against their concentration gradient. The energy may be in the form of ATP, but may also be in other forms. Differential permeability to ions sets up potential differences across membranes
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Passive Transport Mechanisms Diffusion Limited to small molecules, relatively non-polar, also gases (O 2 ) Channels Aqueous pores through membrane Highly selective Ions, water Passive transporters Change conformation with each solute passed
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Na, K ATPase (NKA) Active Transport 0
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Na,K-ATPase Maintains Na + , K + gradients (Na + is high outside, low in, K + is reverse) Uses 1 molecule of ATP per cycle, moving three Na + out per 2 K + in) Electrogenic (i.e. leads to voltage difference across the membrane) Change in conformation, intermediate is phosphorylated: P type ATPase Uses 40% of the ATP in a resting cell 0
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Change in Conformation Due to Phosphorylation/Depohosphorylation 0
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Inhibitors of NKA Digitalis Ouabain Inhibitors of ATP production These materials block the function of the pump, therefore allowing the gradients of Na + and K + to dissipate. 0
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P-Type H + /K + ATPase in Stomach Prilosec 0
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This note was uploaded on 04/08/2008 for the course BIOL 301 taught by Professor Tepperman during the Winter '08 term at University of Cincinnati.

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Lecture 14 Active Transport then Membrane Potentials -...

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