The Golgi apparatus actively participates in the secretion process, that is, the process by which finished products are released out of the cell which produced them. Human cells produce all kinds of secretion proteins. But certain molecules like insulin, which transports sugars, are too big to pass through a standard door. The cell has a special entrance and exit system for these kinds of molecules. Once they have entered, enzymes retrieve the sugar carried by the insulin and bring it to the mitochondria, the cell’s energy factories. Special ducts comprising the “endoplasmic reticulum” are in charge of logistics and transportation within the cell.