In the mode of transport known as active transport, materials, including molecules and other substances move from an area of low concentration to an area of higher concentration, or the flow of particulates is against the concentration gradient of the cell. Due to this alternate movement of substances that is different from passive transport, energy is required for the transport of said particles. The form of energy can come from many different sources whether it be the proton motive force, and ATP. Specifically carrier proteins help assist in the movement of certain particles that cannot easily bypass the plasma membrane of a cell.
