The Golgi apparatus (GA), also called Golgi body or Golgi complex, is a series of five to eight cup-shaped, membrane-covered sacs that look something like a stack of deflated balloons. The GA is the distribution and shipping department for the cell's chemical products. It modifies proteins and lipids (fats) that have been built in the endoplasmic reticulum and prepares them for export as outside of the cell. The number of GAs in each cell varies according to its function, but animal cells generally contain between ten and twenty per cell.
Proteins and lipids built in the smooth and rough endoplasmic reticulum bud off in tiny bubble-like vesicles that move through the cytoplasm until they reach the GA. The vesicles fuse with the GA membrane and release the molecules into the organelle. Once inside, the compounds are further processed by the GA, which adds molecules or chops tiny pieces off the ends. Once completed, the product is extruded from the GA in a vesicle and directed to its final destination inside or outside the cell. The exported products are secretions of proteins or glycoproteins that are part of the cell's function in the organism. Other products are returned to the endoplasmic reticulum or become lysosomes.
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