What is endoplasmic reticulum write it’s function

Endoplasmic reticulum is a tubular sac like cellular organelles enclosed by a continuous single layered membrane and situated just after the nucleus in most of the prokaryotic cells. It has many different functions but played a very important role in protein sorting.                        

LOCATION: It’s generally present in most of the eukaryotic cells including plant cells. It is located associating with the nuclear membrane.

PROPERTIES:

  1. The entire endoplasmic-reticulum is covered by a continuous single layered membrane.
  2. It is the largest organelle in most of the eukaryotic cell. It occupied almost 10% of the total cell volume.

TYPES: There are two types of ER- Rough endoplasmic reticulum (RER) and Smooth endoplasmic reticulum (SER).

Rough ER: In this type of ER is covered by ribosomes associated on the outer surface. These are mainly consisting with cisternae.     

Smooth ER: the ER which does not associate with ribosomes on their surface. This ER mainly consisting with the tubules and vesicles.

Endoplasmic reticulum
Endoplasmic reticulum

TYPICAL ULTRASTRUCTURE OF ER: ER is tubular sac like organelle in appearance. It is covered by a single layered membrane consisting of lipid and protein.  It contains some special structures. These are mainly three types- 1. Cisternae, 2. Tubules and 3. Vesicles. Inside the cell a fluid filled mosaic area is present known as the endoplasmic matrix.    

FUNCTION: The main function of ER is protein processing and sorting. But it has many other roles.

  1. The ribosomes present on the surface of RER play a vital role in protein synthesis.
  2. It acts as the storage organ for some cellular material and transport them through the tubules.
  3. The SER present in the liver cells help to destroy the toxicity of toxins and some drugs.
  4. Some enzymes, present in the ER play a vital role in digestion.

NOTABLE: Endoplasmic Reticulum, present in the cytoplasm of the muscle cell, known as sarcoplasmic reticulum. In the cells of scrotum and adrenal cortex a huge number of SER is present.

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