How Does the Potassium Channel Maintain Selectivity for Potassium Versus

question 17

Multiple Choice

How does the potassium channel maintain selectivity for potassium versus sodium ions?

• A) The ion size is the determining factor.
• B) The size of the ion and associated waters relative to the pore size are the determining factors in channel selectivity.
• C) Dehydration of the potassium ion is compensated energetically by interactions with oxygen atoms in the selectivity filter, which is not possible with sodium ions.
• D) Potassium ions associate with six molecules of water while sodium associates with four, thus allowing selectivity.
• E) None of the answers is correct.

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