Which protein forms pores that allow selective ion flow across the membrane?

Which protein forms pores that allow selective ion flow across the membrane?

• A. Receptor Protein
• B. Enzymatic Proteins
• C. Channel Protein
• D. Carrier Protein

Answer: (C)

Channel proteins form a pore that spans the membrane, creating a continuous, hydrated path through which ions can diffuse. The pore’s lining and size determine which ions can pass, giving it selectivity, and many channels can open or close in response to voltage, ligands, or other signals to regulate flow. This makes them specialized for rapid, selective ion movement across membranes. By contrast, receptor proteins bind signaling molecules without forming a passage for ions, enzymatic proteins drive chemical reactions rather than transport solutes, and carrier proteins bind a solute and change shape to shuttle it across the membrane—typically without forming a permanent pore. Thus, the property of forming a pore for selective ion flow specifically points to channel proteins.

Channel proteins form a pore that spans the membrane, creating a continuous, hydrated path through which ions can diffuse. The pore’s lining and size determine which ions can pass, giving it selectivity, and many channels can open or close in response to voltage, ligands, or other signals to regulate flow. This makes them specialized for rapid, selective ion movement across membranes.

By contrast, receptor proteins bind signaling molecules without forming a passage for ions, enzymatic proteins drive chemical reactions rather than transport solutes, and carrier proteins bind a solute and change shape to shuttle it across the membrane—typically without forming a permanent pore. Thus, the property of forming a pore for selective ion flow specifically points to channel proteins.