A&P Lecture 1.6: Golgi Complex

This is an in depth  explanation of the Golgi Complex as a part of the cell. This lecture note is linked to A&P Lecture 1: The Cell

ANATOMY AND PHYSIOLOGY LECTURE 1.4

GOLGI COMPLEX

The Golgi complex, also called the Golgi apparatus, consists of a stack of several flattened sacs . This is something like a stack of pancakes, but the Golgi sac “pancakes” are hollow, with cavities called cisternae within each sac. One side of the stack faces the endoplasmic reticulum and serves as a site of entry for vesicles from the endoplasmic reticulum that contain cellular products. The other side of the stack faces the plasma membrane, and the cellular products somehow get transferred to that side. This may be because the products are passed from one sac to the next, probably in vesicles, until reaching the sac facing the plasma membrane. Alternatively, the sac that receives the products from the endoplasmic reticulum may move through the stack until reaching the other side. By whichever mechanism the cell product is moved through the Golgi complex, it becomes chemically modified and then, in the sac facing the plasma membrane, is packaged into vesicles that bud off the sac. Depending on the nature of the cell product, the vesicles that leave the Golgi complex may become lysosomes, or secretory vesicles (in which the product is released from the cell by exocytosis), or may serve other functions.

The reverse of exocytosis is endocytosis, as previously described; the membranous vesicle formed by that process is an endosome. . This reverse pathway is called retrograde transport, because proteins within the extracellular fluid are brought into the cell and then taken to the Golgi apparatus and the endoplasmic reticulum. Some toxins, such as the cholera toxin, and proteins from viruses (including components of HIV) rely on retrograde transport for their ability to infect cells.