23. During cotransport, a sodium-potassium pump uses energy
to pump 3 sodium ions out of a cell, and 2 potassium ions into the cell.
As the sodium ions pass back into the cell through a coupled
protein channel, they provide energy to bring glucose molecules into the cell
against its concentration gradient (from low to high concentration).
This 'coupling' allows the cell to accumulate high concentrations
of glucose within the cell.
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