So they oxidize fuel molecules at the same exact time. When they use energy to break down these fuel molecules, they establish an electrochemical gradient of protons, hydrogen ions, and what they establish is a gradient in which we have a high outside concentration and a low inside concentration. And so what happens is we have this Simporter shown here in green, and it allows the spontaneous movement of these protons from the outside to the inside. Free energy is released. That free energy is taken in and is used to basically transfer sugar molecules, in this case lactose molecules. And we have a higher concentration of lactose on the inside than on the outside.