Which of the following membrane ion channels open and close in response to changes in the membrane potential?

• A. voltage-gated channels
• B. chemically gated channels
• C. mechanically gated channels
• D. nongated channels

Answer: (A)

Verified step by step guidance

1. Understand the types of ion channels: Ion channels are proteins that allow ions to pass through the membrane in response to various stimuli. The main types include voltage-gated, chemically gated, mechanically gated, and nongated channels.
2. Define voltage-gated channels: These channels open and close in response to changes in the membrane potential. They are crucial for the initiation and propagation of action potentials in neurons and muscle cells.
3. Differentiate from other channels: Chemically gated channels open in response to binding of a chemical messenger (ligand), mechanically gated channels respond to physical deformation, and nongated channels (leak channels) are always open and allow ions to move along their gradient.
4. Identify the correct answer: Since the question asks for channels that respond to changes in membrane potential, voltage-gated channels are the correct answer.
5. Review the role of voltage-gated channels: These channels are essential in the function of excitable cells, such as neurons and muscle cells, where they help propagate electrical signals by opening in response to changes in voltage across the cell membrane.