Principles of Membrane Transport

Question 1

2 classes of membrane transport proteins

Answer 1

Transporters (active / passive)

Channels (passive)

Question 2

Active transporters

Answer 2

Active transp. move solutes against electrochemical gradient by using energy provided by ATP hydrolysis, by a downhill flow of another solute or by light

Question 3

Ion channels…

Answer 3

…form aqueous pores across lipid bilayer -> allow inorganic ions of approptiate size / charge to pass the membrane down the electrochemical gradients

…open transiently in response to a specific stimulus in membrane

Question 4

Action potentials

Answer 4

Votage gated cation channels are responsible for generation of action potentials in electrically excitable cells

Is propagated along axons and transmitted into neighbor neurons through chemical / electrical synapses

Question 5

In chemical synapses

Answer 5

…transmitter-gated ion channels convert chemical signals to electrical signals

Question 6

Exicatory neurotransmitter (e.g. glutamate, acetylcholine)

Answer 6

Open transmitter-gated action channels => depolarize postsynaptic membrane

Question 7

Inhibitory neurotransmitters (e.g. glycin, GABA)

Answer 7

Open transmitter-gated chloride or potassium channels => hyperpolarize postsynaptic membrane

INHIBITS ACTIONPOTENTIALS BY INCREASING STIMULUS REQUIRED TO MOVE MEMBRANE POTENTIAL TO ACTIONPOTENTIAL