13 — Biological membranes, membrane transport, electric properties of membranes

Question 1

What is the permeability constant?

Answer 1

Question 2

Give the equation describing the flux of material transported across a membrane due to concentration difference between two compartments separated by the membrane.

Answer 2

Question 3

What does it mean that phospholipids are amphipathic molecules?

Answer 3

Question 4

What are the possible forms of motion of a lipid molecule in a membrane?

Answer 4

Question 5

What are the possible phase states of biological membranes?

Answer 5

Question 6

What changes in the properties of the fatty acid side chains increase the transition temperature of a membrane?

Answer 6

Question 7

How does cholesterol change the fluidity of lipid membrane?

Answer 7

Question 8

What is the magnitude of the lateral diffusion constant of lipids and proteins in biological membranes?

Answer 8

Question 9

Which methods can be used to measure the lateral diffusion of proteins in biological membranes?

Answer 9

Question 10

For what kind of molecules is the permeability of biological membranes the highest?

Answer 10

Question 11

How can membrane proteins be classified on their function?

Answer 11

Question 12

What are the extra- and intracellular concentrations of Na+, K+ and Ca+ ions?

Answer 12

Question 13

What is passive transport?

Answer 13

Question 14

What is active transport?

Answer 14

Question 15

What is primary active transport?

Answer 15

Question 16

What is secondary active transport?

Answer 16

Question 17

What is simple diffusion across biological membranes?

Answer 17

Question 18

What is facilitated diffusion?

Answer 18

Question 19

What are the properties or facilitated or carrier-mediated diffusion?

Answer 19

Question 20

What kind of ion channels do you know based on their mode of activation?

Answer 20

Question 21

What is the function of ionophores

Answer 21

Question 22

How can ionophores be grouped according to the mechanism of ion transport?

Answer 22

Question 23

List the factors contributing to the maintenance of resting membrane potential.

Answer 23

Question 24

Write the Nernst equation.

Answer 24

Question 25

What is the equilibrium potential of an ion?

Answer 25

Question 26

Are the ions on the two sides of the membrane of a living cell in thermodynamic equilibrium? Why?

Answer 26

Question 27

Describe the relationship between net fluxes of major permeating ions at the resting membrane potential.

Answer 27

Question 28

Give the definition and unit of flux.

Answer 28

Question 29

Give the Goldmann-Hodgkin-Katz equation.

Answer 29

Question 30

Give the definition and unit of conductivity.

Answer 30

Question 31

Give the current carried by ion **x** through the cell membrane if the membrane potential is **Em**.

Answer 31

Question 32

Define the action potential and interpret the ionic basis of its generation.

Answer 32

Question 33

How do the concentrations of Na+ and K+ in the intra- and extracellular spaces change during a single action potential?

Answer 33

Question 34

What causes the abrupt membrane potential changes during an action potential in a neuron?

Answer 34

Question 35

What is the role of the Na+/K+ ATPase in the membrane potential changes during a single action potential? Why?

Answer 35

Question 36

What is the principle of voltage-clamp?

Answer 36

Question 37

List the methods that can be used for measuring the membrane potential of living cells.

Answer 37

Question 38

What kind of currents can be measured by patch-clamp?

Answer 38

Question 39

What are the most important features of ion channels?

Answer 39

Question 40

What is the range of the voltages corresponding to the R waves of an ECG?

Answer 40

Question 41

Give the Einthoven-Waller rule and interpret the variables in the formula.

Answer 41

Question 42

What is the meaning of an ECG curve in the case of unipolar and bipolar leads?

Answer 42