What cellular structure is primarily associated with protein synthesis?

Ribosomes are the cellular structures responsible for protein synthesis. They can be found freely floating in the cytoplasm or attached to the rough endoplasmic reticulum. Ribosomes translate messenger RNA (mRNA) sequences into amino acid chains, effectively building proteins based on the genetic information carried by mRNA. This process is crucial for cell function, as proteins serve a multitude of roles, including structural, enzymatic, and regulatory functions.

The other structures listed, while important for various cellular processes, do not play a direct role in the synthesis of proteins like ribosomes do. Centrioles are involved in cell division and the organization of microtubules, the smooth endoplasmic reticulum is primarily involved in lipid synthesis and detoxification, and the Golgi apparatus is responsible for modifying, sorting, and packaging proteins for secretion or delivery to other organelles. Each of these structures contributes to cell function, but ribosomes are specifically tasked with the assembly of proteins, making them the primary site of protein synthesis.