Which organelle is primarily responsible for modifying, sorting, and packaging proteins for secretion or delivery?

• A. Mitochondria
• B. Lysosome
• C. Golgi apparatus
• D. Rough endoplasmic reticulum

Answer: (C)

Proteins destined for secretion or delivery are synthesized in the rough endoplasmic reticulum and then pass to the Golgi apparatus. The Golgi acts as the cell’s processing and shipping center: it adds or trims carbohydrate groups and other modifications, sorts proteins based on destination signals, and packages them into vesicles for secretion or delivery to specific locations such as the plasma membrane or lysosomes. The key idea is that the Golgi handles the final processing and precise packaging that prepares proteins for their outside-the-cell or targeted-internal destinations. While the rough ER handles initial protein synthesis and folding, and mitochondria and lysosomes have other roles (energy production and degradation, respectively), only the Golgi combines modification, sorting, and packaging in one centralized step.