Aquaporins are proteins that control the passage of water molecules across a 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. Which of the following do you conclude?
A) These two forms of aquaporin will have identical sequences of amino acids.
B) These two forms of aquaporin will have different sequences of amino acids.
C) You will have to sequence the proteins to compare their primary structure, because it should have no effect on pore diameter.
D) These two forms of aquaporin have identical primary structure but differ in their tertiary structure.

Question

Quizplus · Accepted Answer

The pore diameter of a protein is determined by its three-dimensional structure, which is in turn determined by the sequence of amino acids (primary structure). Different sequences of amino acids will fold into different structures, potentially leading to variations in pore size among aquaporins.

Aquaporins Are Proteins That Control the Passage of Water Molecules