Golgi bodies are found in all types of eukaryotic cells, including plants, animals and protists. These strangely shaped organelles act as a molecular sorting station, directing many of the proteins and carbohydrates used by the body to their correct locations after tagging them with structural modifications and destination information.
What Golgi Bodies Look Like
The Golgi apparatus looks like a stack of pancakes, and these stacks are called cisternae. Each cisterna is made up of a two-layer membrane surrounding a central liquid-filled area. There are usually four to eight stacks in a single Golgi complex, but in some organisms there can be as many as sixty. The number of Golgi complexes in each animal cell is typically between ten and twenty.
The Golgi apparatus is not attached to any other organelle, but floats freely in the cell. Each Golgi body has two "ends", the cis face and the trans face. The cis face is closest to the nuclear membrane and the endoplasmic reticulum, while the trans face is oriented outward toward the plasma membrane of the cell.
The Functions of the Golgi Apparatus
The main functions of the Golgi complex are processing proteins synthesized in the endoplasmic reticulum (ER) and directing molecules made in various areas of the cell to their future locations in or out of the cell. Some of the modifications made inside the Golgi complex include:
- attaching polysaccharides to proteins to form carbohydrates
- cutting proteins into smaller active fragments
- incorporating phosphates onto protein molecules
- addition of a sulfate group to molecules
In addition to modifying molecules made elsewhere in the cell, the Golgi apparatus also makes a few of its own products. Some of the most important molecules created in the Golgi complex are the lysosomes, molecules that operate to digest dead or unnecessary components in the cell, thereby keeping the cell clean and free of debris, and complex sugars.
How the Golgi Complex Works
Vesicles sent from the endoplasmic reticulum fuse to the cis face of a Golgi body, where they release their contents into the complex. The molecules released from the vesicle make their way through the layers of the Golgi body, where they are modified according to the type of molecule they are. Once the modifications are complete and the molecule has made its way across the Golgi complex, the modified molecule exits through the trans face and is directed to its final destination in the cell or to the cell membrane for transport out of the cell.
Sources
Molecular Expressions Cell Biology: The Golgi Apparatus
Lodish et al., Molecular Cell Biology. W.H. Freeman and Company. 2004
Mullins, C. The Biogenesis of Cellular Organelles. Springer, 2004
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