Question

When transporting charged molecules across a membrane, which of the following is/are TRUE?

1) When moving chloride ions in nerve cells, the movement is with both concentration and electrochemical gradients.
2) ΔG is dependent on electrochemical potential.
3) Keq is always equal to zero.
4) ΔG° is always equal to one.
5) Membrane potential is not a factor.

Answer 1

When transporting charged molecules across a membrane, both the concentration gradient and the membrane potential (electrical force) are involved. The movement of chloride ions in nerve cells is with both the concentration and electrochemical gradients.

Step-by-step explanation:

When transporting charged molecules across a membrane, there are two forces at work: a chemical force (the concentration gradient) and an electrical force (the effect of the membrane potential on the ions' movement). These two forces together create an electrochemical gradient. In the case of moving chloride ions in nerve cells, the movement is with both the concentration and electrochemical gradients. The electrochemical gradient is influenced by the difference in charge between the inside and outside of the cell, which creates a membrane potential. Therefore, membrane potential is a factor in the transport of charged molecules across a membrane.