What is the primary function of the endoplasmic reticulum?

The primary function of the endoplasmic reticulum (ER) is to synthesize proteins and lipids. The ER is a crucial organelle within eukaryotic cells, comprising two main types: rough and smooth. The rough ER is studded with ribosomes, which are the sites of protein synthesis. These proteins are often destined for secretion, insertion into membranes, or for use within the cell. In contrast, the smooth ER is involved in lipid synthesis, metabolism, and the detoxification of harmful substances.

By serving these vital roles in synthesizing both proteins and lipids, the endoplasmic reticulum is integral to maintaining cellular structure and function. This role is essential for various cellular processes, including growth, repair, and the overall metabolic activity of the cell. Other options do not accurately describe the function of the endoplasmic reticulum, as transporting genetic material relates more to nucleic acids and ribonucleic processes, digesting cellular waste pertains to lysosomes, and producing energy is primarily associated with mitochondria.