Question

Describe with the help of a diagram the structure of Golgi body and state its function.

Answer 1

Golgi apparatus is a complex cytoplasmic structure made up of smooth membrane saccules or cisternae, a network of tubules with vesicles and vacuoles, which takes part in membrane transformation, secretion, and production of complex biochemicals. The shape and size of Golgi body are not fixed. They depend upon the physiological state of the cells. Usually the Golgi body is made up of four parts - cisternae, tubules, vesicles, and vacuoles.

1. Cisternae: Golgi body consists of a stack of generally 4-8 membrane-bound saccules or cisternae. The saccules are freq curved to give a definite polarity to the Golgi body. One face of the apparatus is convex while the other is concave.
2. Tubules: They form a complicated network towards the periphery and maturing face of the apparatus. Actually, tubules arise due to fenestrations of the cisternae. They have a diameter of 30-50 nm. The tubules interconnect the different cisternae.
3. Vesicles: They are small sacs of 20-80 nm diameters. The vesicles are found attached to the tips of tubules at various levels in the network. They are of two types, smooth and coated.
   
4. Golgian vacuoles: They are expanded parts of the cisternae which have become modified to form vacuoles. The vacuoles develop from the concave or maturing face. Golgian vacuoles contain the amorphous or granular substance. Some of the Golgian vacuole functions as lysosomes.

Functions:

1. All glandular cells depend upon Golgi body for concentrating and packaging their products inside a soluble proteins coat.
   
2. The Golgi body brings about membrane transformation, that is, converting one type of membrane into other types.
   
3. Proteins synthesized by the rough endoplasmic reticulum and lipids synthesized by smooth endoplasmic reticulum reach the cisternae of the Golgi body. Here, they combine with carbohydrates to form glycoproteins and glycolipids.