Final answer:
Gated channels are proteins that allow molecules to pass through the cell membrane in a controlled manner. Examples include voltage-gated ion channels responsive to electrical changes, ligand-gated ion channels that function upon ligand binding, mechanosensitive ion channels that react to mechanical stress, and aquaporins for water transport.
Step-by-step explanation:
Gated channels or transporters are specialized proteins found in cell membranes. These proteins help control the passage of substances, such as ions and water, across the cell membrane. Gated channels are crucial to a variety of cellular processes including but not limited to transmitting electrical signals, maintaining a stable internal environment, and controlling muscle contractions. A gated channel may be influenced by various stimuli, allowing it to open or close and thus regulate the flow of molecules or ions.
Examples of Gated Channels/Transporters
- Voltage-gated Ion Channels: These channels respond to changes in the electrical properties of the cell membrane. A typical example is the sodium channels in nerve and muscle cells, which undergo changes during action potentials.
- Ligand-gated Ion Channels: These channels open or close in response to a specific ligand (e.g., a neurotransmitter) binding to the protein, such as the receptors that control the entry of calcium or sodium ions into a cell.
- Mechanosensitive Ion Channels: These channels are influenced by mechanical forces that physically distort the membrane, thus opening the gate and allowing ions to flow through.
- Aquaporins: These are not ion channels, but specialized channels for the transport of water across cell membranes, playing a crucial role in maintaining fluid balance within various tissues.
Each type of gated channel possesses specificity for certain ions or molecules, serving to maintain the necessary electrochemical gradients and homeostasis within the cell.