The Golgi Apparatus

The Golgi apparatus is a structure familiar to most Eukaryotic cells, including plant and animal cells. It is responsible for the shipping and receiving of molecules within, and out of the cell. Plants and animals may have several or even hundreds of these membrane bound organelles per cell.

The Golgi apparatus is membranous organelle that appears under an electron microscope as a multi-layered stack of flattened sacs. These sacks are referred to as cisternae. Cisternae are not connected, but remain in very close proximity. Their function is to receive and synthesize molecules within the cell. They also prepare molecules for exiting the cell. (Campbell & Reece)

Material that is being handled by the Golgi is received and sent using small capsules called transport vesicles. These vesicles can come from three places with in the cell. One location is the Endoplasmic Reticulum . The ER sends material from the cell nucleus to be processed by the Golgi. Another way that these vesicles are formed is through endocytosis. When a cell engulfs extracellular molecules, it sends them directly to the Golgi in a transport vesicle. The vesicle will attach to the Golgi, and release its contents into the membrane. After the Golgi apparatus has synthesized the material, it will repackage it into a transport vesicle, and send it to a specific location. (Campbell & Reece)

The Golgi structure is indicative of its function. One side of the organelle ,the cis face, is the receiving side of the structure. All vesicles bound for the Golgi apparatus enter here. The cis face has a polar charge that allows vesicles to bond easily with its sticky surface. The other side is called the trans face, which has no charge. After material has been synthesized by the Golgi, it migrates to the trans face. At the trans face, material will retrieve the membrane that it donated to the cis face while entering the Golgi. This helps regulate the size of the Golgi, and keeps exiting material in tact. After the material is placed back into a transport vesicle, it will embark on a new journey. (Campbell & Reece)