The Golgi apparatus is an important organelle that is present in almost every eukaryotic cell. Perhaps the only cells in which this complex is absent are red blood cells of vertebrates. The functions of this structure are very diverse. It is in the tanks of the apparatus that all compounds produced by the cell are accumulated, after which they are further sorted, modified, redistributed and transported.
Despite the fact that the Golgi apparatus was discovered back in 1897, and to this day some of its functions are being actively studied. Consider a more detailed features of its structure and functioning.
Golgi apparatus: structure
This organelle is a collection of membrane tanks that are closely adjacent to each other, resembling a stack. The structural and functional unit is considered a dictiosome.
Dictiosome is a separate, independent part of the Golgi apparatus, which consists of 3 - 8 tanks closely adjacent to each other. The stack of these membrane tanks is surrounded by a system of small vacuoles and vesicles - this is how substances are transported, as well as dictiosomes communicate with each other and other cellular structures. As a rule, animal cells have only one dictiosome, while in plant structures there can be many of them.
In the dictiosome, it is customary to separate two ends - the cis and trans sides. The cis-side faces the nucleus and the granular endoplasmic reticulum. The synthesized proteins and other compounds are transported here in the form of membrane vesicles. At this end of the dictosomes new tanks are constantly being formed.
The trans side faces the cell membrane. As a rule, it is a little wider. This includes compounds that have already passed all the stages of modification. Small vacuoles and vesicles, which transport substances to the necessary organelles of the cell, constantly come off the lower tank.
Golgi apparatus: functions
As already mentioned, the functions of organelles are very diverse.
- Here, a modification of newly synthesized protein molecules is carried out. In most cases, a carbohydrate, sulfate or phosphorus radical is attached to the protein molecule. Thus, the Golgi apparatus is responsible for the formation of a plasma membrane protein, enzymes, and lysosome proteins.
- The Golgi apparatus is responsible for the transport of modified proteins to specific areas of the cell. Small vesicles, which contain the finished proteins, are constantly separated from the trans side.
- Here, the formation and transport of all lysosome enzymes takes place.
- In the cavities of the tanks, the accumulation of lipids occurs, and subsequently the formation of lipoproteins - a complex of protein and lipid molecules.
- The Golgi apparatus of the plant cell is responsible for the synthesis of polysaccharides, which then go on to form the cell wall of the plant, as well as mucus, pectins, hemicelluloses and waxes.
- After dividing the plant cell, the Golgi complex takes part in the formation of the cell plate.
- In the sperm, this organelle takes part in the formation of acrosome enzymes, with the help of which the destruction of the membranes of the egg occurs during fertilization.
- In the cells of the protozoa, the Golgi complex is responsible for the formation of contractile vacuoles, which regulate the osmotic pressure.
Of course, this is not a complete list of all the functions performed. Modern scientists are still conducting a wide variety of studies using the latest technology. It is likely that in the next few years the list of functions of the Golgi complex will grow significantly. But today it can be said with accuracy that this organelle supports the normal life of both the cell and the whole organism.