How is exocytosis different from active transport?

This is a common and understandable mistake that is made since essentially both of these processes refer to molecules being moved out of the cytoplasm of a cell using energy. There is however a major difference between the two. Exocytosis is the transportation, usually in bulk, of molecules out of the cell in vesicles. For example, the release of neurotransmitters from the presynaptic neurone into the synaptic cleft is achieved by exocytosis via a vesicle. This is also the process used for large molecules such as glucose which otherwise could not move in and out of cells. Active transport however uses carrier proteins in the cell membrane and moves molecules against their concentration gradient using ATP. This means that unlike exocytosis which by its name is only restricted to movement out of the cell, active transport can take place both in and out of a cell. Additionally, the movement of these molecules is not in bulk, rather usually one by one since the carrier protein forms a channel for this movement in and out of the cell. An example of active transport is the sodium – potassium pump. Ultimately the take away point to remember is that exocytosis uses vesicles, and active transport uses carrier proteins.