What is the primary function of the endoplasmic reticulum?

The endoplasmic reticulum (ER) primarily functions in the synthesis of proteins and lipids, as well as their transport within the cell. This organelle is divided into two types: rough ER, which is studded with ribosomes and is primarily involved in the synthesis of proteins destined for secretion or for use in membranes, and smooth ER, which is involved in lipid synthesis, detoxification, and calcium ion storage. The continuous network of the ER allows it to not only synthesize these biomolecules but also to facilitate their movement to other parts of the cell, such as the Golgi apparatus for further processing and distribution. This transport is vital for maintaining cellular functions and responding to the cell's needs. The roles of the other options, such as energy production or genetic information storage, are carried out by different organelles, like mitochondria and the nucleus, respectively.