structure and functions of golgi apparatus:

Describe the structure and functions of golgi apparatus.

Introduction to golgi apparatus:

The golgi apparatus is a collection of membrane bound vesicles,sac ,or tubules,which is generally located close to the nucleas.

Golgi apparatus is continuous with the endoplasmic reticulum.

It is named after the discoverer Camillo Golgi.

The golgi apparatus is also known as golgi complex or golgi bodies.

Golgi apparatus is present in all the cell except the red blood cell.

In general there is present one golgi apparatus in each cell ,but some of the cells may have more than one golgi apparatus.

The Golgi apparatus is especially prominent in cells that are specialized for secretion of glycoproteins,such as the goblet cells of the intestinal epithelium.

The Golgi apparatus is regarded as the "post office of the cell" and the "shipping department of the cell".

Structure of golgi apparatus:

The Golgi apparatus consists of a collection of a flattened, membrane enclosed compartments,called cisternae(singular -cisterna).

There is present four functional regions in each cisternae : the cis Golgi network , medial-Golgi, endo-Golgi,and trans-Golgi network.

There is no existence of any constant structure of Golgi body. The diameter of the Golgi body is about 60-70 Angstrom. Under Electron Microscope the main structures of Golgi apparatus are:

Lamellae/Cisternae :

These are consisting of unit membrane in which some liquid material is present. There is present almost 3-20 cisternae in each cell.

Vesicles:

There is present three types of vesicles in the Golgi apparatus,these are :

1.Flattened vesicles

The most prominent vesicles present in the Golgi body is flattened vesicles. Flattened vesicles loke like tubules in a longitudinal section.

2. Secretory vesicles:

The secretory vesicles mainly contains protein materials. The contents of the secretory vesicles are ultimately discharged at its cell surface as zymogen granules.

Normally the secretory vesicles are not visible under Electron Microscope, but they are visible when they are budded off from the distended peripheral end flattened vesicles.

3.Micro vesicles:

These vesicles are small and the diameter of these vesicle is about 40 micrometer.

Vacuoles:

There is some big round shaped vacuoles are present at the end part of the cisternae. These vacuoles are known as Golgian vacuoles.

Functions of Golgi apparatus:

Packaging of proteins ,which are synthesized in the rough endoplasmic reticulum in to the vesicles.
Sulphate groups are added to the protein molecules in the Golgi apparatus.
Golgi apparatus helps in the formation of lysosomal enzymes.
Golgi apparatus also has an important role in the synthesis of carbohydrates and complex proteins.
Golgi apparatus has an important role in the apoptosis process.
Synthesis of proteoglycans is carried out by the Golgi body .
The Golgi enzymes present in membranous disks of cisternae carry out modification of proteins which travel through them.