Biology

Golgi Apparatus Formation and Structure with Functions

In this post, you are going to learn about the Golgi apparatus step by step with Diagrams.

This post includes:

  • what is the Golgi apparatus?
  • structure of the apparatus
  • functions of apparatus
  • characteristics and diseases
  • Lots more

So if you want to get benefits from this post you’ll love this post.

Let’s Dive right in..

What is the Golgi Apparatus

A Golgi body, also known as a Golgi apparatus, is a cell organelle that helps process and package proteins and lipid molecules, Golgi apparatus was discovered by Mr. Chemello Golgi, in 1898. The Golgi apparatus is specially developed in cells that have functions related to the secretion of substances, such as cells of the nervous or endocrine system. It present only in eukaryotic cells. especially proteins destined to be exported from the cell. Named after its discoverer, Camillo Golgi, the Golgi body appears as a series of stacked membranes. As the Golgi apparatus, a cellular organelle is known whose function is to handle the proteins synthesized by the endoplasmic reticulum to transform them and export them to the rest of the organism. Proteins, as they pass through the Golgi apparatus, undergo a modification process before being released.

 

As such, the Golgi apparatus is one of the structures that make up the interior of cells, both in animal organisms and in plant organisms. However, its structure is more complex in animal cells.

The Golgi apparatus is an organelle that contains all eukaryotic cells (those that have a defined nucleus in their cytoplasm ) and that is part of the endomembrane system.

It is a vital organelle in the synthesis of many of the cell’s proteins and lipids, which functions as a packaging plant: it synthesizes, packages and distributes the substances generated by the cell to their respective destinations in the cytoplasm.

Cells can have one or more of these Golgi apparatus (in fact plants have hundreds of them), generally located near the cell nucleus and endoplasmic reticulum, in the cytoplasm.

Depending on the cell, each apparatus may contain a variable number of cisterns, that is, “bags” stacked to contain proteins or lipids. In this way, it is an organelle essential for cell life and for the fulfillment of organic synthesis.

What is the Golgi Apparatus?

The Golgi apparatus is an organelle that contains all eukaryotic cells (those that have a defined nucleus in their cytoplasm ) and that is part of the endomembrane system.

It is a vital organelle in the synthesis of many of the cell’s proteins and lipids, which functions as a packaging plant: it synthesizes, packages and distributes the substances generated by the cell to their respective destinations in the cytoplasm.

Cells can have one or more of these Golgi apparatus (in fact plants have hundreds of them), generally located near the cell nucleus and endoplasmic reticulum, in the cytoplasm.

Depending on the cell, each apparatus may contain a variable number of cisterns, that is, “bags” stacked to contain proteins or lipids. In this way, it is an organelle essential for cell life and for the fulfillment of organic synthesis.

Structure of Golgi apparatus

The apparatus consists of stacks of sacs. These sacs are flattened and membranous bound (surrounded by a membrane). These stacked sacs are called cisternae. The cisternae with associated vesicles are called the Golgi apparatus or Golgi complex. The Golgi complex is a complex system of interconnected tubules. These tubules are present around the central stacks. Golgi apparatus is made up of a series of attached cisterns, which we can classify according to their position and function as follows:

  • Cis cistern
  • Intermediate tanks
  • Trans cistern

Cis cistern

The cis cistern is the one closest to the rough endoplasmic reticulum (RER), from which it receives transition vesicles containing the proteins to be transformed.

Intermediate tanks

The intermediate cisterns are those that are found in the intermediate zone of the Golgi apparatus, between the cis and trans cisterns.

Trans cistern

The trans cistern is one that is directed to the plasma membrane and linked to the smooth endoplasmic reticulum (REL). It is from here that the transport vesicles leave to act in different places in the body.

The Golgi apparatus encompasses three distinct functional regions:

  • Cis-Golgi region. The innermost portion, and closest to the rough endoplasmic reticulum (RER), from which the vesicles with newly synthesized proteins come.
  • Medial region. A transition zone between the Cis and the Trans region.
  • Trans-Golgi region. It is closer to the plasma membrane, and it is there that the membranes are modified so that each protein and lipid is sent to its specific destination.

However, the full functioning of the Golgi apparatus has not yet been fully unraveled.

Formation of Golgi apparatus

  1. The smooth endoplasmic reticulum (SER) forms transport vesicles by budding.
  2. These vesicles fuse with cisternae. This fusion takes place toward the forming face of the Golgi complex. This forming face is the outer convex surface of the Golgi complex. It is present towards the SER.
  3. A vesicle is transferred towards the maturing face. The maturing face is the inner concave surface of the Golgi complex. It is present towards the plasma membrane. This maturing face breaks up the cisternae from vesicles and forms secretory vesicles.golgi apparatus

Functions of Golgi apparatus

Golgi complex performs the following functions:

The Golgi apparatus has the function of modifying, storing, and exporting proteins synthesized in the endoplasmic reticulum to different parts of the body.

Proteins enter the in and are then transported through a series of cisternae in which enzymes act to modify them.

In this process, the proteins receive a fragment of carbohydrates or lipids, with which glycoproteins, glycolipids, and lipoproteins are produced.

Subsequently, the proteins will be packed in membranes to form two types of vesicles:

  • Secretory vesicles, which carry proteins to the outside of the cell to be released.
  • Storage vesicles or lysosomes, where proteins remain in the cell’s cytoplasm until the moment of being exported.

In this sense, the operation of the apparatus is similar to that of a post office, which is responsible for receiving, classifying, and distributing correspondence.

The general function of the Golgi apparatus is to “package” and “mark” each protein vesicle so that it can be successfully delivered to its destination, just as a central product packaging plant does.

In this sense, the apparatus checks that the product has no defects, that it is complete and assembled, joining simple molecules to form other complex ones and identifying them correspondingly according to their destination: other cell organelles or the cell membrane, to be secreted to the environment.

Other functions of the Golgi apparatus include:

  • Absorb substances from the cytoplasm. Such as water, sugars, or lipids, especially what comes from the formation of secretory vesicles.
  • Form secretory vesicles. Create the protein sacs that carry their contents out of the cell.
  • Create enzymes.  Many enzymes originate from this organelle since they are proteins with specific functions.
  • Create specialized substances. To contribute with the cell membrane, with the constitution of specialized cells (such as sperm), proteins such as milk, etc.
  • Segregate glycoproteins.  The proteins that contain carbohydrates (sugars), are constituted inside.
  • Produce lysosomes. Organelles are responsible for cellular digestion.

Cell secretions: Golgi complex is concerned with cell secretions. For example, in mammals, the pancreas secretes granules. These granules contain enzymes that help in the process of digestion. There are the following steps in the process of cell secretions.

  1. The ribosomes synthesize the protein part of the cell secretions.
  2. The endoplasmic reticulum transfers it to the Golgi apparatus.
  3. Golgi complex converts the secretion to form granules.
  4. Finally, granules are exported outside by the cell membrane.
  5. Transportation: Golgi complex transport the proteins or enzymes outside the cell.

Formation of Glycoproteins and Glycolipids:

It is the most important function of the Golgi complex. They add carbohydrates to protein and lipids to form glycoproteins and glycolipids.golgi apparatus relation

(This figure shows the relationship of endoplasmic reticulum with Golgi complex, lysosome, and plasma membrane).

GOLGI APPARATUS 

We explain what the Golgi apparatus is, what its structure is like, and what its functions are. Also, its characteristics and diseases.

Golgi apparatus

 

Name Golgi apparatus

The name of the Golgi apparatus comes from its discovery at the beginning of the 20th century, when the Italian scientist Camilo Golgi, winner of the Nobel Prize in Medicine in 1906, managed to describe them in great detail, based on the initial observations in 1897 of the Spanish Santiago Ramón and Cajal, with whom he shared the award.

The use of the electron microscope from 1950 onwards confirmed Golgi’s descriptions quite accurately.

Golgi apparatus dictyosomes

The Golgi apparatus consists of dictyosomes, which are a set of membranous saccules, that is, of submicroscopic, flattened, and stacked containers, surrounded by a tubular network and by a set of vesicles.

Inside each dictyosome are the cisternae where the proteins are “packed”. In reality, talking about dictyosomes, the Golgi apparatus, or the Golgi system is basically talking about the same thing.

Golgi apparatus size

The size of the dictyosomes and the cisternae of the Golgi apparatus is variable, depending on the type of cell, the species, and the metabolic moment of the same. It is generally estimated to measure between 1 and 3 microns in diameter.

Types of gallbladder

Transport vesicles that cross the apparatus can be of the following types:

  • Constitutive. They contain proteins whose destination is the exterior of the cell, through constitutive secretion (exocytosis) that takes place in the plasma membrane.
  • Regulated. Vesicles of secretion that are also destined for the outside of the cell, but not immediately: they will remain stored in the cell waiting for their triggering stimulus to occur. This process is called regulated secretion.
  • Lysosomal.  Its destination is the lysosomes: organelles generated by the Golgi system itself, responsible for breaking down the external substances that enter the cell (cellular digestion).

Golgi apparatus transport mechanism

The exact mechanism of how proteins move through the Golgi is not yet clear. But there are two main hypotheses about how it happens:

  • Cisterns maturation model. The generation of the new cisterns would “push” the old ones through the apparatus.
  • Vehicle transport model.  This theory assumes the Golgi apparatus as a stable and static entity, and that the movement of the vesicles is rather due to the nature of the proteins inside.

 

Function of lysosomes

The lysosomes generated by the Golgi apparatus contain hydrolytic and proteolytic enzymes, capable of breaking down the material of extracellular or intracellular origin, that is, in charge of cellular digestion.

Lysosomes are pockets of enzymes that, if released into the cell, would destroy it completely. Therefore, these organelles have a specialized membrane that prevents it. Lysosomes are common to animal cells, but not so to plant cells

Importance of the Golgi apparatus

This apparatus is of vital importance in the protein generation circuit of cells and, by extension, of living beings. It serves as a link between the inside of the cell (the nucleus and the endoplasmic reticulum, where proteins are produced) and the outside of it. It is a crucial biochemical transport mechanism.

Golgi-related diseases

There are some cases in which defects of the Golgi apparatus translate into diseases such as Mucolipidosis II, a disease that affects the mechanism of identification of proteins of the Golgi apparatus so that cellular digestion cannot be carried out correctly and the lysosomes are they fill with undigested material. It is a congenital ailment with fatal consequences, which does not allow life to exceed 7 years of age.

Many other ailments under the current study are thought to originate from defects, such as Pelizaeus-Merzbacher disease, Angelman syndrome, wrinkled skin syndrome, and Duchenne muscular dystrophy, among others.

 

 

Related Articles

Back to top button
Close