Role of Endoplasmic Reticulum:

Endoplasmic reticulum is located in Cell membrane. It is found in continuation with the outer most part of the nuclear membrane. Microscopic observation of Endoplasmic reticulum is folded. ER protrudes in to cytoplasm. Folded Endoplasmic reticulum provides larger surface area so that the chemical reaction process is possible without obstacles. The added advantage of folding results in sac formation.

Types of ER:

Depending on ER association with ribosome they are classified as below

• Rough Endoplasmic reticulum
• Smooth Endoplasmic reticulum

Eukaryotic ER:  Endoplasmic reticulum is usually associated with ribosome. Their appearance is not smooth as they form tiny knobs over the ER. Hence they are referred to as Rough Endoplasmic reticulum. In RER (Rough Endoplasmic Reticulum) the synthesis of protein is more. Synthesized protein move into lumen. Lumen is internally folded structured sacs. Refolding of ER exposes a hydrophobic surface which helps them to float in cell membrane. Proteins which are synthesized move inside the lumen resulting in the formation of Golgi apparatus. The areas where there are no knobs surfaces appear smooth and they are referred to as smooth endoplasmic reticulum. This smooth endoplasmic reticulum helps in production and processing of protein and lipid destruction.

Prokaryotic ER: Prokaryotic cell membranes get folded in cell organelles as there is no large surface area. But they help in cytosol compartment formation. Part of the metabolic process occurs in the area immediate cell membrane referred to as Periplasm. Interior surface of the periplasmic cell membrane folds to form mesosomes for oxidative metabolism.