And we'll discuss that in much greater detail when we get to that subject. So basically, this type of active transport requires not only energy, it also requires a specialized type of integral protein. And two types of active transport exist. In one active transport, we use the ATP energy molecule to move that molecule against the electrochemical gradient. In a second type of active transport, known as secondary active transport, we first use an ATP molecule to create an electric potential gradient, an electrochemical gradient, and then we use that electrochemical gradient to move our molecule across our semipermeable membrane. So, to summarize, let's take a look at the following diagram.