Membrane Dynamics Part II

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Membrane Dynamics Part II

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University of Southern California
Bisc 307l - General Physiology
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BISC 307L 1st Edition Lecture 3 Current Lecture Membrane Dynamics continued  Primary Active Transport (4) o Called Pumps, against electrical or chemical gradients  Antiports  Move two substances in the opposite direction  Na+/K+ ATPase o Muscle contraction, conformation change in protein o 3 sodium ions for one potassium o contributes to resting membrane potential (electrogenic)  H+/K+ ATPase  Uniports  Pump one kind of ion in one direction across the membrane  Ca2+ ATPase  H+ ATPase  Secondary Active Transport o Energy given up as a ion moves down its gradient is coupled to and powers the movement of another substance against its gradient o Usually Na+ moving against its gradient o Secondary because the ATP is directly used to transport Na+ ions but this ATP comes from other ions o Internal Na+ concentration is 15mM (low)  Creates an electrical or chemical gradient for sodium o Intracellular K+ is kept high 150mM o Antiports

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