What is Golgi apparatus?
What Does Golgi apparatus Mean
The notion of apparatus can refer to the grouping of elements that, acting in a coordinated way and together, perform the same function. There are multiple apparatuses: among them, the Golgi apparatus .
The Golgi apparatus is the organelle found in eukaryotic cells, which is responsible for completing the production process of certain proteins. This apparatus is made up of about eighty dictyosomes , which are groups of small sacs known as saccules . Dictyosomes, flattened in shape, are located one on top of the other and are protected by a membrane.
Golgi apparatus, also called the Golgi apparatus , Golgi body and golgisoma , was discovered by Santiago Ramon y Cajal in 1897 . Later, Camillo Golgi was in charge of accurately describing everything related to this organelle, which ended up adopting the name of the Italian doctor.
The saccules can be grouped in several ways: usually, groups of four to eight saccules are formed, which make up the dictyosomes. Through different tubes, substances can pass from one saccule to another. The external face of the saccules is directed towards the system known as the endoplasmic reticulum .
Among the functions developed by the Golgi apparatus are the production of the acrosome that is part of the sperm and the development of primary lysosomes; the elaboration of plasma membrane; cell secretion; and the alteration of the substances that the rough endoplasmic reticulum synthesizes . In general it can be said that the Golgi apparatus modifies and distributes the macromolecules synthesized by the cell .
Smooth endoplasmic reticulum vesicles
Vesicles are formed in the smooth endoplasmic reticulum that, when joined, create tube-vesicular aggregates that are carried towards the cis region of the Golgi apparatus by means of motor proteins. The latter, for their part, can advance thanks to the guidance of some microtubules and, when they fuse with the membrane of the device, they empty their content into the lumen.
The molecules entering the Golgi apparatus are changed, are marked and then are sent to their ultimate destination. Proteins that are carried to distant parts of the apparatus reach the trans region , and enter a complex network of vesicles and membranes. This is where most of them are marked and sent to their respective destinations through one of the following three types of vesicles, depending on their marker:
* Exocytosis vesicles : are those that contain proteins that will be released into the extracellular environment . After internalization of the proteins, the vesicle closes and goes immediately to the plasma membrane, with which it binds to release the content, in a process known as constitutive secretion . An example of this can be seen when antibodies are released by activated B lymphocytes;
* Secretion vesicles : these are those that also contain proteins that must be released into the extracellular environment, although it is important to note that, after their formation, these vesicles are stored in the cell and are kept there waiting the signal that tells them to start their activity. At that moment, they move towards the plasma membrane, where they discharge their contents, just as exocytosis vesicles do. The name of this process, which takes place when neurons release neurotransmitters, is regulated secretion ;
* Lysosomal vesicles : these vesicles are responsible for transporting proteins to lysosomes, small organelles that contain a large number of acid hydrolases. Regarding the type of proteins, they can be membrane or digestive enzymes. To transfer its contents to the lysosome, the vesicle must fuse with a late endosome, as occurs when digestive proteases are delivered to the lysosomes.