What are the main components of the rough endoplasmic reticulum?

The rough endoplasmic reticulum (RER) is characterized by its surface being studded with ribosomes, which gives it a "rough" appearance under a microscope. These ribosomes are the sites of protein synthesis, where amino acids are assembled into proteins based on messenger RNA (mRNA) templates. The RER's primary function is to facilitate the synthesis of proteins that are either secreted from the cell, used within the cell, or incorporated into cellular membranes.

Membrane proteins are particularly significant as they play crucial roles in cell signaling, transport, and maintaining cell structure. The rough endoplasmic reticulum helps in the initial stages of membrane protein synthesis, folding, and modification. Thus, the presence of both ribosomes and membrane proteins reflects the specialized function of the rough endoplasmic reticulum in the production and processing of proteins.

The other options do not correctly capture the primary components associated with the rough endoplasmic reticulum. While fatty acids and sugars can be found in various cellular contexts, they do not serve as identifying features of the RER. Similarly, while nucleic acids are vital for several cellular processes, they are not a characteristic component of the rough endoplasmic reticulum itself.