Exam 1: Membrane-Bound Receptors

Question 1

Two types of gated ion channels:

Answer 1

Voltage-gated

Ligand-gated

Question 2

Resting membrane potential:

Answer 2

-70mV

Question 3

Define depolarization/excitation:

Answer 3

Membrane potential moves from -70mV towards 0mV

Question 4

Define hyperpolarization/inhibition:

Answer 4

Membrane potential moves away from -70mV (becomes more negative)

Question 5

How each type of channel contributes to AP propagation:

Answer 5

Ligand-gated ion channels begin AP

Voltage-gated continue it

Question 6

Define agonist:

Answer 6

Ligand that binds to receptor and activates it

Question 7

Define antagonist:

Answer 7

Ligand that binds to receptor that prevents it from activating

Question 8

Three types of antagonists:

Answer 8

Orthosteric
Allosteric
Pore blocker

Question 9

Define orthosteric antagonist:

Answer 9

Acts on the main binding site of the receptor

Question 10

Define allosteric antagonist:

Answer 10

Acts on accessory binding site of receptor

Question 11

Define pore blocker antagonist:

Answer 11

Physically obstructs the ion channel

Question 12

Two main types of membrane-bound receptors:

Answer 12

Ligand-gated ion channels

G-protein coupled receptors

Question 13

Relative transmission speed of ligand-gated ion channels:

Answer 13

Very fast

Question 14

Structure of ligand-gated ion channels:

Answer 14

Several subunits around a central ion pore

Question 15

Two major families of ligand-gated ion channels:

Answer 15

Cys-loop receptors

Ionotropic glutamate receptors

Question 16

Examples of cys-loop receptors:

Answer 16

Nicotinic ACh
Glycine
5HT-3

Question 17

Examples of ionotropic glutamate receptors:

Answer 17

AMPA receptor
NMDA receptor
Kainate receptor

Question 18

Structure of cys-loop receptors:

Answer 18

Pentameric

Question 19

Structure of ionotropic glutamate receptors:

Answer 19

Tetrameric

Question 20

Cys-loop receptors are named for:

Answer 20

The loop formed by a disulfide bond between two cysteines

Question 21

Five types of cys-loop subunits:

Answer 21

Alpha, beta, gamma, delta, epsilon

Question 22

Excitatory cys-loop receptors:

Answer 22

Nicotinic ACh

Serotonin

Question 23

Inhibitory cys-loop receptors:

Answer 23

Glycine

GABAa

Question 24

Subunit that obstructs cys-loop receptor pore:

Answer 24

Transmembrane domain of the alpha subunit

Question 25

Mechanism by which agonist binding activates cys-loop receptor:

Answer 25

Changes conformation to move obstructing part of alpha subunit

Question 26

Drugs that act on cys-loop receptors:

Answer 26

Nicotine
Varenicline (Chantix)
Barbiturates
Benzos
ETOH
Ambien

Question 27

Drugs that act on glutamate receptors:

Answer 27

Ketamine (NMDA)

Aniracetam (AMPA)

Question 28

Nicotinic ACh receptors (nAChRs) are found:

Answer 28

Neuromuscular junction

CNS

Question 29

Difference between NMJ and neuronal nAChR subunits:

Answer 29

NMJ receptors have α, β, δ, γ subunits

Neuronal only have α, β

Question 30

Ions that pass through nAChRs:

Answer 30

Na+
K+
Some Ca++

Question 31

Define desensitized state:

Answer 31

Ligand is bound, but gate is closed

Question 32

Glutamate receptors are excitatory/inhibitory?

Answer 32

Excitatory

Question 33

Ions that pass through glutamate receptors:

Answer 33

Na+
K+
Ca++ (NMDA only)

Question 34

Composition of glutamate receptor subunits:

Answer 34

Binding site
Four transmembrane domains
Second TM domain is what forms ion pore

Question 35

Binding sites on NMDA receptor:

Answer 35

Two glutamate

Two glycine

Question 36

of binding sites required to be occupied for glutamate receptor channel to open:

Answer 36

All four

Question 37

Define long term potentiation:

Answer 37

More often a neuron fires, the stronger the synapse gets

Question 38

Long term potentiation is critical for:

Answer 38

Learning and memory

Question 39

NMDA receptors are normally blocked by _____ and this block is relieved by ______.

Answer 39

Mg++; voltage (depolarization)

Question 40

Potentiation occurs in the neuron via addition of:

Answer 40

AMPA receptors

Question 41

Relative speed of G-protein coupled receptors:

Answer 41

Much slower than ligand-gated

Question 42

% of genome dedicated to GPCR coding:

Answer 42

3%

Question 43

Class A GPCRs:

Answer 43

Adrenergic receptors

Muscarinic ACh receptors

Question 44

Class B GPCRs:

Answer 44

Parathyroid hormone receptors

Question 45

Class C GPCRs:

Answer 45

Metabotropic glutamate receptors

GABAb receptors

Question 46

Alpha subunit action upon GPCR activation:

Answer 46

Binds to GPCR, GDP gets phosphorylated, binds to target protein, GTP gets hydrolysed

Question 47

Three main types of G proteins:

Answer 47

GαQ
GαS
Gαi

Question 48

Gαq activation causes:

Answer 48

PIP2 –> IP3 + DAG + PKC

Release of Ca++ from stores

Question 49

IP3 + DAG are:

Answer 49

Lipid messengers

Question 50

Gαq activation causes:

Answer 50

ATP –> cAMP + PKA

Question 51

PKC and PKA are important because:

Answer 51

Small enough to enter the nucleus

Question 52

Gαi activation causes:

Answer 52

Inhibition of receptor

Question 53

Molecule that “tags” GPCRs that have been bound too long:

Answer 53

β-arrestin

Question 54

What happens to GPCRs ‘tagged’ with β-arrestin:

Answer 54

Vesicle forms around GPCR and internalizes it

Question 55

Cholera toxin works by:

Answer 55

Disrupting hydrolysis of GTP to GDP

Question 56

Increased GTP from cholera toxin interference causes:

Answer 56

High cAMP levels
Activation of Cl- pumps
Cl- release into the intestinal lumen
Na+, K+, bicarb follow Cl-
Osmosis draws water into lumen