In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by ________.
A) cotransport proteins
B) ion channels
C) pores in the plasma membrane
D) passive diffusion across the plasma membrane

Question

Quizplus · Accepted Answer

Cotransport proteins, also known as symporters or antiporters, are membrane transport proteins that couple the movement of one ion down its electrochemical gradient (usually sodium or hydrogen ion) to the movement of another ion against its electrochemical gradient (usually glucose or amino acids). This allows for the creation and maintenance of multiple ion electrochemical gradients across the plasma membrane even with only one or two proton pumps present.

In Some Cells, There Are Many Ion Electrochemical Gradients Across