Question:
Events occurring during signal propagation in a chemical synapse are given below.
P: Postsynaptic membrane potential changes.
Q: Synaptic vesicle fuses with the presynaptic membrane.
R: Action potential depolarizes the presynaptic terminal.
S: Neurotransmitter binds to receptors on the postsynaptic membrane.
T: Neurotransmitter is released into the synaptic cleft.
The correct sequence of occurrence of these events is:
Events occurring during signal propagation in a chemical synapse are given below.
P: Postsynaptic membrane potential changes.
Q: Synaptic vesicle fuses with the presynaptic membrane.
R: Action potential depolarizes the presynaptic terminal.
S: Neurotransmitter binds to receptors on the postsynaptic membrane.
T: Neurotransmitter is released into the synaptic cleft.
The correct sequence of occurrence of these events is:
P: Postsynaptic membrane potential changes.
Q: Synaptic vesicle fuses with the presynaptic membrane.
R: Action potential depolarizes the presynaptic terminal.
S: Neurotransmitter binds to receptors on the postsynaptic membrane.
T: Neurotransmitter is released into the synaptic cleft.
The correct sequence of occurrence of these events is:
Show Hint
Always trace the physical pathway of the signal: electrical (action potential R) $\rightarrow$ calcium influx and vesicle fusion (Q) $\rightarrow$ release into cleft (T) $\rightarrow$ receptor binding (S) $\rightarrow$ postsynaptic electrical change (P).
Updated On: Jun 16, 2026
- R, Q, T, S, P
- Q, R, T, S, P
- R, T, Q, P, S
- Q, R, P, S, T
Show Solution
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Question:
The question asks for the correct temporal sequence of events during chemical synaptic transmission.
Step 2: Detailed Explanation:
• Synaptic transmission is a highly coordinated process that allows neurons to communicate with each other using chemical messengers.
• The process begins when an action potential travels down the axon and reaches the presynaptic terminal, causing depolarization of the membrane (Event R).
• This depolarization opens voltage-gated calcium ($\text{Ca}^{2+}$) channels, allowing calcium ions to rush into the presynaptic terminal.
• The influx of $\text{Ca}^{2+}$ triggers the fusion of neurotransmitter-containing synaptic vesicles with the presynaptic membrane (Event Q).
• Upon fusion, the neurotransmitter molecules are released into the synaptic cleft via exocytosis (Event T).
• The released neurotransmitter molecules diffuse across the narrow synaptic cleft and bind to specific receptor proteins located on the postsynaptic membrane (Event S).
• The binding of neurotransmitters to these receptors (which are often ligand-gated ion channels) causes them to open, leading to ion flow and a subsequent change in the postsynaptic membrane potential (Event P).
• Thus, the correct sequence of events is: R $\rightarrow$ Q $\rightarrow$ T $\rightarrow$ S $\rightarrow$ P.
Step 3: Final Answer:
Therefore, the correct sequence of occurrence of these events is R, Q, T, S, P.
The question asks for the correct temporal sequence of events during chemical synaptic transmission.
Step 2: Detailed Explanation:
• Synaptic transmission is a highly coordinated process that allows neurons to communicate with each other using chemical messengers.
• The process begins when an action potential travels down the axon and reaches the presynaptic terminal, causing depolarization of the membrane (Event R).
• This depolarization opens voltage-gated calcium ($\text{Ca}^{2+}$) channels, allowing calcium ions to rush into the presynaptic terminal.
• The influx of $\text{Ca}^{2+}$ triggers the fusion of neurotransmitter-containing synaptic vesicles with the presynaptic membrane (Event Q).
• Upon fusion, the neurotransmitter molecules are released into the synaptic cleft via exocytosis (Event T).
• The released neurotransmitter molecules diffuse across the narrow synaptic cleft and bind to specific receptor proteins located on the postsynaptic membrane (Event S).
• The binding of neurotransmitters to these receptors (which are often ligand-gated ion channels) causes them to open, leading to ion flow and a subsequent change in the postsynaptic membrane potential (Event P).
• Thus, the correct sequence of events is: R $\rightarrow$ Q $\rightarrow$ T $\rightarrow$ S $\rightarrow$ P.
Step 3: Final Answer:
Therefore, the correct sequence of occurrence of these events is R, Q, T, S, P.
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