Question

Channel proteins allow ions that would not normally pass through the cell membrane to go through the channel. What properties of the proteins are responsible for this?

• A. The channels are often composed of charged or polar $R$ groups.
• B. The channels are often composed of hydrophobic $R$ group.
• C. $a$ and $b$
• D. None of these

Answer 1

The correct option is A The channels are often composed of charged or polar $R$ groups.

Facilitated diffusion, therefore, allows polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions, to cross the plasma membrane. Two classes of proteins that mediate facilitated diffusion are generally distinguished.

So, the correct option 'The channels are often composed of charged or polar R groups'.