Smooth and Rough Endoplasmic Reticulum

The term Endoplasmic Reticulum was given by Garneir in the year 1897 and called it ergastoplasm. While in the year 1945 the Endoplasmic Reticulum was seen under electron microscope by Porter, Keith and Fullam. The word reticulum means network and was given by Porter.

Structure of Endoplasmic Reticulum

• It is a double membrane system
• It consists of tube-like membranes distributed all across the cytoplasm
• It is present in close proximity to plasma membrane on outside while the nuclear membrane on the internal side 
• It is connected to nuclear membrane 
• It has two types that are closely connected that are the smooth Endoplasmic Reticulum and Rough Endoplasmic reticulum

Endoplasmic reticulum functions

• It is involved in membrane biogenesis, which is the process by which the cell membrane is formed with the help of Protein and lipid 
• It is involved in transportation of protein from Rough Endoplasmic reticulum and lipid from Smooth Endoplasmic reticulum
• It’s primary function is to provide backbone to the cell

Rough Endoplasmic reticulum

The word rough is due to the presence of ribosomes that makes it look rough when seen under a microscope. The outer surface of Ribosome is a membrane bound organelle that are around 13 million in number in the Rough Endoplasmic reticulum of the liver cell. Though the are distributed all along the cell but due to its protein producing capacity it is in close proximity to the Golgi apparatus that is involved in packaging if the Protein Structure produce by RER ( Rough Endoplasmic reticulum).

The ribosomes help in translation process that is process of amalgamation of protein. The Rough Endoplasmic reticulum works with ribosomes by taking the polypeptide from cytosol and further assembling them and transporting them to the Golgi apparatus for packaging. The Rough Endoplasmic reticulum produces the proteins for various other organelles like the Golgi apparatus, lysosomes and for the endoplasmic reticulum as well.

The rough endoplasmic reticulum has various sections through which protein has to pass to finally reach the packaging stage.The protein first passes through the folding section wherein it is folded to get the lock and key site. Later it passes through the protein quality control section wherein the structure quality is checked and if the protein is not properly structured then it is recycled. Post that the final step is transferred to the Golgi apparatus in the form of vesicles.

Smooth Endoplasmic reticulum

These are tubular structures that don’t have Ribosomes in the surface and are exclusively involved with lipid , be it lipid metabolism or lipid hormone processing. As in the case of liver cells , adrenal cortex and various glands .

Smooth Endoplasmic reticulum is also involved in detoxification of drugs .It converts the harmful organic compound into simpler water soluble compounds that are safe .

Smooth Endoplasmic reticulum is widely present in liver cells where it converts the ethanol from consumption of alcohol or the other drugs like barbiturates from overdose to safer forms by detoxification.

For detoxification smooth Endoplasmic reticulum  doubles their area so that the process happens on a large scale and rapidly and later it comes back to its original size which is caused by release of calcium ions from the endoplasmic reticulum itself.

Difference between Smooth and Rough Endoplasmic reticulum

• The Smooth Endoplasmic Reticulum lacks the ribosomes that produce protein while the Rough Endoplasmic reticulum has ribosomes on the surface
• Cells that produce protein have more rough endoplasmic reticulum while the cells that produce lipid or fat have more Smooth Endoplasmic Reticulum
• Smooth Endoplasmic reticulum is  tubular while the Rough endoplasmic reticulum is made of flat sac-like structure called cisternae 
• Smooth Endoplasmic reticulum produces lipid , steroidal hormones while the Rough Endoplasmic Reticulum produces proteins
• Smooth Endoplasmic reticulum is involved in detoxification of drugs while rough endoplasmic reticulum is not 
• Smooth Endoplasmic reticulum produced by Rough Endoplasmic reticulum
• Smooth Endoplasmic reticulum is present near cell membrane while the Rough Endoplasmic reticulum is present near the cytoplasm also in close affinity with Golgi apparatus
• Smooth Endoplasmic reticulum gives rise to spherosomes while rough endoplasmic reticulum is involved in synthesis of lysosomes , Smooth Endoplasmic reticulum itself
• Smooth Endoplasmic reticulum are present in cells like adipocytes ,cortex while the Rough Endoplasmic reticulum is present in cells like goblet cells and pancreatic cells
• Smooth Endoplasmic reticulum is less stable and the post cell destruction they die but in the case of Rough Endoplasmic reticulum it lives for some time after cell death. It is more stable in comparison to smooth Endoplasmic reticulum
• Smooth Endoplasmic reticulum transport the product of Rough Endoplasmic reticulum to Golgi apparatus
• Smooth Endoplasmic Reticulum is crucial in production of phospholipid for cell membranes

Conclusion

Endoplasmic Reticulum is an important organelle in the animal and plant cell. It is involved in Protein Production system and also in lipid metabolism. It is the part of the endomembrane system. The two subunits perform the specific function and are crucial functioning of the cell.