Golgi Apparatus Structure

The image below shows the structure of the Golgi apparatus. The cis face of the organelle is closest to the endoplasmic reticulum. The trans face is the side furthest from the nucleus, which secretes vesicles to various parts of the cell. Further, there are a number of lumens and cisternae through which products flow. These appear as a series of flattened sacs stack on each other, much like the endoplasmic reticulum.

Golgi Apparatus Location

The Golgi apparatus is situated in between the endoplasmic reticulum and the cell membrane. Most often, the Golgi appears to be an extension of the endoplasmic reticulum which is slightly smaller and smoother in appearance. However, the Golgi apparatus can be easily mistaken for smooth endoplasmic reticulum. Although they look similar, the Golgi is an independent organelle which has different functions.

Theory of Golgi Apparatus Function

The most prevalent theory of how the Golgi apparatus forms is the cisternal maturation model. This model suggests that the sacs themselves tend to move from the cis face to the trans face of the Golgi apparatus over time. New sacs are formed closest to the endoplasmic reticulum. These sacs “age” as they move towards the trans face of the Golgi apparatus and their product becomes fully mature.

Specific Products

It may seem like there could never be enough lipids to produce the continual flow of cell membrane needed to continually make transport vesicles between the endoplasmic reticulum and the Golgi apparatus. However, there are constantly segments of cell membrane being produced and recycled by the endoplasmic reticulum, Golgi apparatus, lysosomes, and other organelles in the cell, as well as the outer cell membrane itself. The Golgi apparatus and endoplasmic reticulum work together to produce new cell membrane, as well as recycle the cell membranes of vesicles by merging two membranes when vesicles are absorbed.

The Golgi also creates lysosomes. These sacs contain digestive materials. The sacs are pinched off from the Golgi apparatus, and they are used to process materials which have been phagocytized or to digest organelles which no longer function. The lysosome delivers raw ingredients to the endoplasmic reticulum.

Golgi Apparatus in Plant Cells

While this article primarily discusses the operation of the Golgi apparatus within animal cells, plant cells also have a Golgi apparatus. In fact, plant cells may contain hundreds of these organelles.

Within plant cells, the Golgi apparatus serves the additional function of synthesizing the major polysaccharide molecules which help form the cell wall. To do this, plants often have many more Golgi bodies than an animal cell. Further, plant cells do not contain lysosomes. These digestive organelles are replaced in the plant with the central vacuole, which serves as a large lysosome as well as an organelle to store water. Thus, many vesicles from the Golgi bodies of plants move to the vacuole and fuse their contents with this large organelle.