Which one of the following statements about ligand-gated ion channels is CORRECT?

Question

BlackTom AI · Accepted Answer

Ligand-gated ion channels open when a neurotransmitter (ligand) binds to them, creating a pore that permits ions to flow across the cell membrane and thereby change the postsynaptic cell’s membrane potential.

Relevant knowledge points and concepts:
- Ligand-gated (ionotropic) receptors are membrane proteins that undergo a conformational change on transmitter binding and form an ion-conducting pore. Examples: nicotinic acetylcholine receptors, GABA(A) receptors, glycine receptors, and 5-HT3 receptors.
- They mediate fast synaptic transmission at the postsynaptic membrane (e.g., at neuromuscular junctions and many central synapses).
- Ion selectivity varies by receptor type: some are cation channels (Na+, K+, sometimes Ca2+), others are anion channels (Cl–).
- These are distinct from voltage-gated ion channels (which open in response to membrane depolarization and are concentrated at the axon initial segment) and from G-protein–coupled (metabotropic) receptors (which act via intracellular second messengers).

Step-by-step reasoning:
1. The defining functional feature is opening in response to ligand binding and allowing ions to pass — this matches statement 1.
2. Statement 2 claims they are highly selective and only allow sodium into the neuron. This is false: many ligand-gated channels are nonselective cation channels (permit Na+ and K+, e.g., nicotinic ACh) or are anion-selective (GABA(A) passes Cl–), so “only sodium” is incorrect.
3. Statement 3 misattributes the axon initial segment localization and action potential initiation to ligand-gated channels; in fact voltage-gated Na+ channels at the initial segment initiate action potentials.
4. Statement 4 incorrectly classifies ligand-gated ion channels as G-protein–coupled receptors; GPCRs are metabotropic and signal via second messengers rather than forming pores.

Why the correct answer is correct:
Statement 1 precisely describes the mechanism of ligand-gated ion channels: transmitter binding opens the channel to allow ion movement across the membrane, producing fast synaptic effects.

Conclusion: The correct answer is "Ligand-gated ion channels are opened by binding of a transmitter to allow movement of ions across the cell membrane." This matches the provided answer.

Which one of the following statements about ligand-gated ion channels is CORRECT?单项选择题

类似问题

Which one of the following is characteristic of the events occurring at an excitatory synapse?

Nicotinic acetylcholine (Ach) receptors mediate synaptic transmission at the neuromuscular junction and are an example of .

Acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium/potassium channel and opens it. This is an example of ________.

The membrane receptor on the dendrite that receives the neurotransmitter is a type of ______.

Ion channels located on the plasma membrane of a muscle, which open in response to binding of acetylcholine, are an example of a:

When a nerve cell is stimulated, it triggers the release of the neurotransmitter ligands. These then bind to the gated channel, allowing it to open. The flow of ions into the cell is what propagates the nerve signal. This describes a type of ______.

Using the analogy of an office key opening an office door to describe the action of chemical messengers on an ion channel, which of the following would be equivalent to inserting the correct key into the lock?

Ligand gated ion channels can be found:

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单