Name the three classes of transporters. Explain which one or more of these classes is able to move glucose and which move bicarbonate (HC0₃^–) against an electrochemical gradient. In the case of bicarbonate, but not glucose, the ∆G of the transport process has two terms. What are these two terms, and why does the second not apply to glucose? Why are cotransporters often referred to as examples of secondary active transport?