Active transport is reliant on [[Transport Proteins - Physiology|carrier proteins]] and thus follows the same rules as [[Transport Proteins - Physiology|facilitated diffusion]] in that they are specific have a maximum rate and are subject to competition. Crucially they transport substances against their concentration gradient and so require energy to work. | Active transport is reliant on [[Transport Proteins - Physiology|carrier proteins]] and thus follows the same rules as [[Transport Proteins - Physiology|facilitated diffusion]] in that they are specific have a maximum rate and are subject to competition. Crucially they transport substances against their concentration gradient and so require energy to work. |