The organelle that is a granular body and serves as the site of protein synthesis is the ribosome.
Ribosomes can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum, forming what is known as rough ER. These small structures are composed of ribosomal RNA (rRNA) and proteins, creating a complex that facilitates the translation of messenger RNA (mRNA) into polypeptide chains, which ultimately fold into functional proteins.
Protein synthesis is critical for many cellular processes, including growth, repair, and maintenance. By translating the genetic instructions carried by mRNA, ribosomes play an essential role in the overall functioning of the cell and, by extension, the entire organism.