Aquaporins are proteins that control the passage of water molecules across the cell membrane. The protein forms a pore, or opening, in the membrane.

Aquaporins are proteins that control the passage of water molecules across the cell membrane. The protein forms a pore, or opening, in the membrane. You isolate what you think are two different molecules of aquaporin, and determine that one of the proteins has a larger pore diameter than the second. What can you conclude about the structure of these molecules?