Lectures 6A & 6B (Multiple-Choice)

Which receptor type directly opens an ion channel when a neurotransmitter binds?
A) Metabotropic
B) Ionotropic
C) G-protein-coupled
D) Second-messenger receptor

B) Ionotropic

Which characteristic best describes metabotropic receptors?
A) They directly conduct ions
B) They always cause depolarization
C) They activate G-proteins and intracellular signaling
D) They function only at neuromuscular junctions

C) They activate G-proteins and intracellular signaling

Why are ionotropic receptor responses typically faster than metabotropic responses? A) They directly open ion channels

B) They require multiple second messengers

C) They activate enzymes before affecting membrane potential

D) They require protein synthesis

A) They directly open ion channels

Which type of receptor can produce effects lasting from milliseconds to minutes or longer?

A) Voltage-gated sodium channel

B) Ionotropic receptor

C) Ligand-gated chloride channel

D) Metabotropic receptor

D) Metabotropic receptor

Which statement correctly describes small-molecule neurotransmitter packaging?

A) They are packaged exclusively in the nucleus

B) They are synthesized and packaged in presynaptic terminals

C) They are transported only in dense-core vesicles

D) They are synthesized exclusively in the Golgi apparatus

B) They are synthesized and packaged in presynaptic terminals

Which vesicle type typically stores neuropeptides?

A) Small clear-core vesicles

B) Lysosomes

C) Large dense-core vesicles

D) Endosomes

C) Large dense-core vesicles

How are neuropeptide-containing vesicles transported from the cell body to the terminal?

A) Fast axonal transport

B) Passive diffusion

C) Slow axonal transport only

D) Retrograde diffusion

A) Fast axonal transport

Which neurotransmitter was the first to be discovered?

A) Dopamine

B) Glutamate

C) GABA

D) Acetylcholine

D) Acetylcholine

Which two molecules are required to synthesize acetylcholine?

A) Glutamate and glutamine

B) Acetyl-CoA and choline

C) Tyrosine and dopamine

D) GABA and acetate

B) Acetyl-CoA and choline

Which enzyme catalyzes acetylcholine synthesis?

A) Acetylcholinesterase

B) Glutaminase

C) Choline acetyltransferase

D) Glutamic acid decarboxylase

C) Choline acetyltransferase

Which transporter packages acetylcholine into synaptic vesicles?

A) VAChT

B) ChT

C) EAAT

D) VGLUT

A) VAChT

Which enzyme terminates acetylcholine signaling by breaking down acetylcholine in the synaptic cleft?

A) Glutamine synthetase

B) Choline acetyltransferase

C) Glutaminase

D) Acetylcholinesterase

D) Acetylcholinesterase

What are the products of acetylcholine breakdown?

A) Glutamate and acetate

B) Choline and acetate

C) Acetyl-CoA and glutamine

D) Choline and GABA

B) Choline and acetate

What would happen if acetylcholinesterase activity were inhibited?

A) Acetylcholine synthesis would immediately stop

B) Choline reuptake would increase automatically

C) Acetylcholine would remain in the synaptic cleft longer

D) Nicotinic receptors would become metabotropic

C) Acetylcholine would remain in the synaptic cleft longer

Which transporter returns choline to the presynaptic terminal?

A) ChT

B) VAChT

C) VGLUT

D) GAT

A) ChT

How many subunits form a nicotinic acetylcholine receptor?

A) Two

B) Three

C) Four

D) Five

D) Five

Which subunit contains the acetylcholine-binding site on nicotinic receptors?

A) Beta

B) Alpha

C) Gamma

D) Delta

B) Alpha

What happens when acetylcholine activates a nicotinic receptor?

A) G-proteins activate intracellular enzymes

B) Chloride channels close

C) A ligand-gated ion channel opens

D) Neurotransmitter synthesis stops

C) A ligand-gated ion channel opens

Which ion's passage through nicotinic receptors is emphasized in Lecture 6A?

A) Na+

B) Cl−

C) Mg2+

D) Ca2+

A) Na+

Which statement correctly describes muscarinic acetylcholine receptors?

A) They are pentameric ion channels

B) They directly conduct Na+

C) They have no membrane-spanning domains

D) They are G-protein-coupled receptors

D) They are G-protein-coupled receptors

How many transmembrane helices are found in muscarinic acetylcholine receptors?

A) Five

B) Seven

C) Two

D) Four

B) Seven

Why can muscarinic receptor activation produce either excitation or inhibition?

A) Acetylcholine changes into different neurotransmitters

B) All muscarinic receptors conduct both Na+ and Cl−

C) Different receptor subtypes activate different G-protein signaling pathways

D) Muscarinic receptors contain different numbers of ion-channel pores

C) Different receptor subtypes activate different G-protein signaling pathways

Which cholinergic pathway is particularly associated with learning and memory?

A) Basal forebrain projections to the hippocampus and cortex

B) Spinal motor neurons projecting to skeletal muscle

C) Cerebellar projections to the spinal cord

D) Retinal projections to the thalamus

A) Basal forebrain projections to the hippocampus and cortex

Which cholinergic nuclei are associated with arousal and the sleep–wake cycle?

A) Nucleus basalis and medial septal nucleus

B) Substantia nigra and ventral tegmental area

C) Raphe nuclei and locus coeruleus

D) Pedunculopontine and laterodorsal tegmental nuclei

D) Pedunculopontine and laterodorsal tegmental nuclei

What is the major excitatory neurotransmitter in the CNS?

A) GABA

B) Glutamate

C) Glycine

D) Acetylcholine

B) Glutamate

Why must glutamate be synthesized from precursors within neurons?

A) It is stored only in the nucleus

B) It is destroyed immediately in blood

C) It does not readily cross the blood–brain barrier

D) It cannot be transported into vesicles

C) It does not readily cross the blood–brain barrier

Which enzyme converts glutamine into glutamate?

A) Glutaminase

B) Glutamine synthetase

C) Acetylcholinesterase

D) Glutamic acid decarboxylase

A) Glutaminase

Which transporter packages glutamate into synaptic vesicles?

A) GAT

B) SAT2

C) VAChT

D) VGLUT

D) VGLUT

Which transporters remove glutamate from the synaptic cleft?

A) VMAT

B) EAATs

C) ChT

D) VIAAT

B) EAATs

What is the role of glutamine synthetase in glial cells?

A) It converts GABA into glutamate

B) It degrades acetylcholine

C) It converts glutamate into glutamine

D) It packages glutamate into vesicles

C) It converts glutamate into glutamine

Which transporter moves glutamine out of glial cells?

A) SN1

B) SAT2

C) EAAT

D) VGLUT

A) SN1

Which transporter takes glutamine into presynaptic neurons?

A) SN1

B) VIAAT

C) GAT

D) SAT2

D) SAT2

What is excitotoxicity?

A) Increased GABA-mediated inhibition

B) Neuronal damage caused by excessive excitatory signaling

C) Reduced neurotransmitter synthesis

D) Failure of neuropeptide transport

B) Neuronal damage caused by excessive excitatory signaling

What makes a synapse tripartite?

A) It contains three postsynaptic neurons

B) It releases three neurotransmitters

C) It includes presynaptic and postsynaptic elements plus an astrocyte

D) It contains three types of ion channels

C) It includes presynaptic and postsynaptic elements plus an astrocyte

Which glutamate receptor is the primary mediator of fast excitatory transmission in the brain?

A) AMPA

B) NMDA

C) mGluR

D) GABA-B

A) AMPA

What ion movements are associated with AMPA receptor activation?

A) Cl− influx and Ca2+ efflux

B) Mg2+ influx only

C) K+ influx and Na+ efflux

D) Na+ influx and K+ efflux

D) Na+ influx and K+ efflux

What structural change occurs when glutamate binds an AMPA receptor?

A) The receptor separates into individual subunits

B) The ligand-binding clamshell closes and opens the channel gate

C) A G-protein detaches from the receptor

D) Mg2+ permanently blocks the pore

B) The ligand-binding clamshell closes and opens the channel gate

Why are NMDA receptors called coincidence detectors?

A) They respond only to inhibitory neurotransmitters

B) They open whenever glycine is present

C) They require ligand binding and membrane depolarization

D) They respond only to changes in extracellular potassium

C) They require ligand binding and membrane depolarization

Which co-agonist must bind alongside glutamate to activate NMDA receptors?

A) Glycine

B) GABA

C) Acetylcholine

D) Dopamine

A) Glycine

Which ion blocks the NMDA receptor pore at hyperpolarized membrane potentials?

A) Na+

B) K+

C) Cl−

D) Mg2+

D) Mg2+

What removes the Mg2+ block from NMDA receptors?

A) Increased GABA release

B) Postsynaptic depolarization

C) Acetylcholine degradation

D) Glutamate reuptake

B) Postsynaptic depolarization

Which ion enters through NMDA receptors and acts as an intracellular second messenger?

A) Cl−

B) Mg2+

C) Ca2+

D) K+

C) Ca2+

Which receptor typically produces a slower EPSC with prolonged decay compared with AMPA?

A) NMDA

B) Kainate

C) GABA-A

D) Nicotinic acetylcholine receptor

A) NMDA

Where does glutamate bind on metabotropic glutamate receptors?

A) The ion-channel pore

B) The intracellular G-protein

C) The transmembrane sodium gate

D) The Venus flytrap domain

D) The Venus flytrap domain

Which enzyme converts glutamate into GABA?

A) Glutaminase

B) Glutamic acid decarboxylase

C) Glutamine synthetase

D) Acetylcholinesterase

B) Glutamic acid decarboxylase

Which vitamin provides the precursor for the cofactor required in GABA synthesis?

A) Vitamin B12

B) Vitamin C

C) Vitamin B6

D) Vitamin D

C) Vitamin B6

Which transporter packages GABA into synaptic vesicles?

A) VIAAT

B) EAAT

C) VAChT

D) SAT2

A) VIAAT

Which statement correctly describes GABA-A receptors?

A) They are metabotropic receptors that activate G-proteins

B) They are glutamate-gated calcium channels

C) They are receptors that directly activate adenylyl cyclase

D) They are pentameric ionotropic receptors that conduct Cl−

D) They are pentameric ionotropic receptors that conduct Cl−

How do benzodiazepines affect GABA-A-mediated signaling?

A) They inhibit GABA synthesis

B) They enhance GABAergic inhibition

C) They block all chloride movement

D) They convert GABA-A receptors into GABA-B receptors

B) They enhance GABAergic inhibition

Which mechanism can produce inhibition following GABA-B receptor activation?

A) Direct opening of a chloride pore within GABA-B

B) Direct opening of an AMPA channel

C) Activation of K+ channels through G-protein signaling

D) Removal of Mg2+ from NMDA receptors

C) Activation of K+ channels through G-protein signaling