The Golgi apparatus is a membrane bound organelle found in most cells. It is responsible for packaging proteins into vesicles prior to secretion and therefore plays a key role in the secretory pathway.

In this article we shall look at the structure and function of the golgi apparatus

Structure

The golgi is made of 5-8 folds called cisternae. The cisternae contain specific enzymes creating five functional regions which modify proteins passing through them in a stereotypical way, as follows:

1. Cis-Golgi network: faces the nucleus, forms a connection with the endoplasmic reticulum and is the entry point into the Golgi apparatus.
2. Cis-Golgi: major processing area allowing biochemical modifications.
3. Medial-Golgi: major processing area allowing biochemical modifications.
4. Trans-Golgi: major processing area allowing biochemical modifications.
5. Trans-Golgi network: exit point for vesicles budding off the Golgi surface, packages and sorts biochemicals into the vesicles according to their destination.

Function

The golgi apparatus modifies proteins and lipids that it receives from the endoplasmic reticulum. These biochemicals leave the golgi by exocytosis before being delivered to different intracellular or extracellular targets.

• Protein processing – carbohydrate regions of glycoproteins are altered by addition, removal or modification of carbohydrates.
• Lipid processing – adds phosphate groups and glycoproteins to lipids from the endoplasmic reticulum (such as cholesterol) to create the phospholipids that make up the cell membrane.

Best Regards
Rebecca Pearson
Editorial Manager