What are the structural elements of endoplasmic reticulum ? Explain in detail.

Explanation

The largest of the internal membranes is called the Endoplasmic reticulum (ER). The name endoplasmic reticulum was given by K.R .Porter (1948). It consists of double membrane. Morphologically the structure of endoplasmic reticulum consists of :
1. Cisternae are long, broad, flat, sac like structures arranged in parallel bundles or stacks to form lamella. The space between membranes of cisternae is filled with fluid.
2. Vesicles are oval membrane bound vacuolar structure.

3. Tubules are irregular shaped , branched, smooth walled, enclosing a space.
(i) Endoplasmic reticulum is associated with nuclear membrane and cell surface membrane.
(ii) if forms a network in cytoplasm and given mechanical support to the cell. its chemical environment enables protein folding and undergo modification necessary for their function.
(iii) Misfolded proteins are pulled out and are degraded in endoplasmic reticulum. When ribosomes are present in the outer surface of the membrane it is called as Rough Endoplasmic reticulum (RER), when the ribosomes are absent in the endoplasmic reticulum it is called as Smooth endoplasmic Reticulum (SER).
(iv) Rough Endoplasmic reticulum is involved in protein synthesis and Smooth endoplasmic reticulum are the sites of lipid synthesis.
(v) The smooth endoplasmic reticulum contains enzymes that detoxify lipid soluble drugs, certain chemicals and other harmful compounds.