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Question 1

what is transmembrane potentials

Answer 1

Generated by ion transport and differences in electrical potential existing between the inner and outer surface of biomembranes. That is, there is a difference in the energy required for electric charges to move from the internal to exterior cellular environments and vice versa.

Question 2

Gradient of electrochemical potential

Answer 2

Driving force of the passive transport of charged solutes (ions). For monovalent ions at equilibrium: ΣJi = 0

Question 3

Flux equation for diffusion of ions through membranes

Answer 3

Ji –> see book for equation

Question 4

The Nernst equation

Answer 4

An important relation which is used to determine reaction equilibrium constants and concentration potentials as well as to calculate the minimum energy required in electrodialysis.
–> see euquation in book

Question 5

Membrane mechanism

Answer 5

Equilibrium potential of selectively permeable membrane: take into consideration the concentration gradient and the membrane potential (may be acting in opposing directions)

Question 6

Diffusion potential (liquid junction potential)

Answer 6

Equilibrium membrane potential due to different mobility of anions and cations (the membrane properties are not involved). Diffusion potential occurs also during diffusion in the space without a membrane!
Diffusion potentials decrease with the concentration gradients and are vanished at concentration equilibrium.

Question 7

Interphase potential

Answer 7

Equilibrium potential at the interphase of two immiscible phases (liquid/liquid) due to different solubility of anions and cations in the two phases.

Question 8

Donnan potential

Answer 8

Equilibrium potential due to impermeable membrane for large charged molecules. Part of the small ions are attracted at the side with the large ions: colloid osmotic effect.