Question 1

Which of the following is a distinguishing electrophysiological feature of a gap junction (electrical synapse) compared to a chemical synapse?

Accepted Answer

Rapid, bidirectional transmission of ionic current with little to no delay

Question 2

Which of the following best describes the structure of a gap junction?

Accepted Answer

Connexon channels that directly connect the cytoplasm of two adjacent cells

Question 3

Which of the following is NOT one of the three criteria that define a neurotransmitter?

Accepted Answer

The substance must be able to cross the postsynaptic membrane without a receptor

Question 4

Which of the following statements about the release of small-molecule neurotransmitters and neuropeptides is correct?

Accepted Answer

Small-molecule neurotransmitters are synthesized in the terminal, while neuropeptides are synthesized in the cell body and transported to the terminal

Question 5

Which experimental evidence supports the quantal release of neurotransmitter at the neuromuscular junction?

Accepted Answer

Miniature end-plate potentials (MEPPs) occur spontaneously and EPP amplitudes are multiples of MEPP amplitude

Question 6

Why did Katz and co-workers study end-plate potentials (EPPs) under conditions of low extracellular Ca$$^{2+}$$ concentration?

Accepted Answer

To observe subthreshold EPPs and failures, revealing the quantal nature of release

Question 7

Which of the following best describes the role of Ca$$^{2+} in $$neurotransmitter release?

Accepted Answer

Ca$$^{2+}$$ influx through voltage-gated channels triggers vesicle fusion with the presynaptic membrane

Question 8

Which of the following is a correct sequence of events in chemical synaptic transmission?

Accepted Answer

Action potential invades terminal → Ca$$^{2+}$$ influx → Vesicle fusion → Neurotransmitter release → Neurotransmitter binds postsynaptic receptors

Question 9

Which component of the SNARE complex acts as the Ca$$^{2+}$$ sensor during vesicle fusion?

Accepted Answer

Synaptotagmin

Question 10

A researcher injects BAPTA, a Ca$$^{2+}$$ chelator, into the presynaptic terminal. What is the most likely outcome?

Accepted Answer

Neurotransmitter release is blocked due to the absence of free Ca$$^{2+}$$

Question 11

Which of the following best explains why gap junctions allow for rapid and synchronized firing among coupled neurons?

Accepted Answer

They allow direct passage of ions and small molecules between cells

Question 12

Which of the following is a key difference between electrical and chemical synapses?

Accepted Answer

Chemical synapses have a synaptic delay and are unidirectional, while electrical synapses are rapid and bidirectional

Question 13

Which of the following statements about synaptic vesicle recycling is correct?

Accepted Answer

Vesicle membranes are retrieved via clathrin-mediated endocytosis and recycled

Question 14

A patient is exposed to a toxin that specifically disrupts the function of SNAP-25. Which step in synaptic transmission would be most directly affected?

Accepted Answer

Vesicle docking and priming at the presynaptic membrane

Question 15

Which of the following best describes the quantal hypothesis of neurotransmitter release?

Accepted Answer

Each synaptic vesicle releases a discrete, fixed amount of neurotransmitter corresponding to one quantum

Question 16

Which of the following is a correct statement about the molecular machinery underlying neurotransmitter release?

Accepted Answer

The SNARE complex is formed by synaptobrevin, syntaxin, and SNAP-25

Question 17

Which of the following best explains why neurotransmitter release is Ca$$^{2+}-$$dependent?

Accepted Answer

Ca$$^{2+}$$ binds to synaptotagmin, triggering conformational changes that drive vesicle fusion

Question 18

Which of the following is a real-life application of understanding the quantal nature of neurotransmitter release?

Accepted Answer

Designing drugs that modulate synaptic vesicle release to treat neurological disorders

Question 19

Which of the following statements about the specificity of synaptic contacts is correct?

Accepted Answer

Discrete molecular events and a distinct time delay ensure unidirectional signaling at chemical synapses

Question 20

Which of the following best describes the process of neurotransmitter packaging into synaptic vesicles?

Accepted Answer

Neurotransmitters are loaded into vesicles by vesicular transporters driven by a proton gradient

Synaptic Transmission: Structure, Function, and Mechanisms

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