Golgi apparatus is a small organelle that serves as the center for making, modifying, storing, sorting, and delivering the useful substances produced by a living cell. An organelle is a small, organlike structure within a cell with a specialized function. The Golgi apparatus is found near the cell nucleus in many cells. It is named after the Italian biologist Camillo Golgi, who first described it in 1898. It is also sometimes called the Golgi complex. The Golgi apparatus consists of stacks of flattened, membrane-covered sacs called cisternae. It may include several to hundreds of these stacks.
One part of the Golgi apparatus faces the endoplasmic reticulum. The endoplasmic reticulum is an organelle sandwiched in between the nucleus and the Golgi apparatus. Many of the cell’s proteins are made in the endoplasmic reticulum. The Golgi apparatus works somewhat like a post office. It can receive proteins from the endoplasmic reticulum in packages called vesicles. When a vesicle is received, its contents are sorted and processed within the Golgi apparatus before being sent on in new vesicles to other parts of the cell. A vesicle may even be sent to the outer cell membrane to dump its contents outside the cell.
Vesicles sent out from the Golgi apparatus are formed by material budding off from the cisternae. Vesicles can also form at the cell membrane to bring substances inside the cell. These substances may then be transported to the Golgi apparatus.
An important processing step in the Golgi apparatus is to attach signaling molecules. These molecules are attached like tags to proteins and other materials. The signaling molecules help to ensure that the tagged materials are guided to the places in the cell where they are needed.
