BIOL1025 - Hydrophilic signalling - ligand gates ion channels

Question 1

opening of a channel

Answer 1

change in ion concentration at inner membrane fast and change in potential difference (Na+/K+)
some ions bind to protein = conformational change and signal transduction

Question 2

signalling speed

Answer 2

rapid - millisecond and reverted quickly as well

localised unless amplified

Question 3

fast ligand-gated ion channel examples

Answer 3

nicotinic acetylcholine receptor
glutamate receptor
serotonin (5HT) receptor
GABA receptor
all able to bind to other types of receptors

Question 4

other fast ligand-gated ion channel examples

Answer 4

glycine

extracellular ATP receptors

Question 5

nicotine - in superfamily of ligand gated ion channel

Answer 5

pentamer - differing subunits

a2by𝛿 / a2b3

Question 6

structure of nicotine

Answer 6

5 polypeptides - each have 4 a helices
3 - mainly HP and contact bilayer
1(M2) - amphipathic helix and lines pore

Question 7

alpha (a) subunit

Answer 7

has acetylcholine binding regions (sites)

conformational change when 2-acetylcholine bind to alpha

Question 8

when binding to a subunits

Answer 8

cause rotation - pulling charged residue from pore to open

Question 9

process

Answer 9

ligand binding = transient therefore open channel allow cation enter

Question 10

non-selective of ion channel

Answer 10

permeable for Na+ and K+ but mainly Na+ pass

depolarises cell as membrane potential and Na+ gradient causes Na+ to enter

Question 11

opening Cl- channel

Answer 11

hyperpolarises cell as Cl- enter

Question 12

Cation channels

Answer 12

serotonin (5HT3)

ionotropic glutamate receptors

Question 13

Chloride channels

Answer 13

GABA{A} receptor

glycine

Question 14

nicotine as an example

Answer 14

ionotropic receptor

AKA muscarinic acetylcholine receptor

Question 15

cation

Answer 15

Na+ , Ca2+, K+