Structure of the Cell - Endoplasmic Reticulum (ER)

The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags (vesicles).

There are two types of ER:

• Rough endoplasmic reticulum (RER)
• Smooth endoplasmic reticulum (SER).

RER has ribosomes attached to its surface, which are sites of protein synthesis.

SER helps in the manufacture of fat molecules, or lipids, important for cell function.

• Membrane biogenesis: Some of these proteins and lipids help build the cell membrane. This process is known as membrane biogenesis.
• It always forms a network system. It serves as a channel for the transport of materials (especially proteins) between various regions of the cytoplasm or between the cytoplasm and the nucleus.
• The ER also functions as a cytoplasmic framework, providing a surface for some of the biochemical activities of the cell. E.g., SER also helps in detoxification.

 Endoplasmic Reticulum 

1. ER provides structural support to the cell. It helps transport proteins throughout the cell.
2. The ER detoxifies harmful substances by making them water-soluble so they can be removed from the body.
3. It helps in storing and releasing calcium ions, important for muscle function.
4. It assists in the folding and quality control of newly made proteins.
5. The rough ER is covered with ribosomes, which make proteins, while the smooth ER is involved in lipid production.
6. The ER also plays a role in packaging and sending molecules to other parts of the cell.