Ligand-gated ion channels(LGIC)

Question 1

describe what an ion channel is

Answer 1

ion channel = transmembrane pores made from glycoproteins, that span the membrane and create an ion conducting pathway for selected ions

Question 2

how are ion channels usually regulated

Answer 2

by signals that cause the channel to cycle reversibly between an open(conducting) and closed(non-conducting) conformation shape, known as gating

Question 3

describe what happens when an ion gated channel is open

Answer 3

when open, channels conducts selected ions passively down their electrochemical gradients at extremely fast rates

Question 4

state some different ways in which ion channels are gated

Answer 4

by chemical signals, by transmembrane voltage, by physical stimuli

Question 5

give an example of a LGIC and describe the structure of a LGIC

Answer 5

example = nicotinic acetylcholine receptor
structure = consists of separate glycoprotein sub-units that form a central, ion conducting, channel

Question 6

what does the structure of a LGIC allow it to do

Answer 6

allow very rapid changes in permeability of membrane to certain ions, also allow rapid change in membrane potential

Question 7

describe a simplified sequence of the activation of a LGPC

Answer 7

agonist binds, causes rapid conformational change from closed to open, permits conducting pathway for selected ions, ions then flow down their electrochemical gradient