What is the primary function of the endoplasmic reticulum?

The endoplasmic reticulum (ER) plays a crucial role in the synthesis and transport of proteins and lipids, making that function its primary purpose. The ER exists in two forms: rough and smooth. The rough endoplasmic reticulum is studded with ribosomes, which are sites for protein synthesis. Once proteins are synthesized, they are folded and modified in the rough ER before being packaged into vesicles for transport to other parts of the cell, such as the Golgi apparatus for further processing.

The smooth endoplasmic reticulum, on the other hand, is involved in the synthesis of lipids and detoxification of certain chemicals. It also plays a role in storing calcium ions, which are important for various cellular functions. Thus, the ER can be seen as a critical hub for the production and trafficking of macromolecules needed for the cell’s structure and function.