Chapter 4 Flashcards

active transporters
Transmembrane proteins that actively move ions into or out of cells against their concentration gradients. Their source of energy may be ATP or the electrochemical gradients of various ions.
ATPase pumps
Membrane pumps that use the hydrolysis of ATP to translocate ions against their electrochemical gradients.
co-transporters
Active transporters that use the energy from ionic gradients to carry multiple ions across the membrane in the same direction.
electrogenic
Capable of generating an electrical current; usually applied to membrane transporters that create electrical currents while translocating ions.
ion exchangers
Membrane transporters that exchange intracellular and extracellular ions against their concentration gradient by using the electrochemical gradient of other ions as an energy source.
ligand-gated ion channels
Ion channels that respond to chemical signals rather than to the changes in membrane potential generated by ionic gradients. The term covers a large group of neurotransmitter receptors that combine receptor and ion channel functions into a single molecule.
macroscopic currents
Ionic currents flowing through large numbers of ion channels distributed over a substantial area of membrane.
microscopic currents
Ionic currents flowing through single ion channels.
patch clamp
An extraordinarily sensitive voltage clamp method that permits the measurement of ionic currents flowing through individual ion channels.
pore
Structural feature of an ion channel that allows ions to diffuse through the channel.
pore loop
An extracellular domain of amino acids, found in certain ion channels, that lines the channel pore and allows only certain ions to pass.
voltage-gated
Term used to describe ion channels whose opening and closing is sensitive to membrane potential.
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