Final answer:
The Golgi apparatus is the cell organelle that processes, packages, and exports proteins. It works closely with the rough ER and ribosomes, receiving and modifying proteins before packaging them into vesicles for transport.
Step-by-step explanation:
The part of the cell responsible for processing, packaging, and exporting proteins is the Golgi apparatus. The Golgi apparatus receives proteins from the rough endoplasmic reticulum (ER), where ribosomes synthesize these proteins. It then modifies, sorts, and packages these proteins for secretion or for use within the cell.
Once processed, proteins are encapsulated into vesicles, which can transport the proteins to different parts of the cell or out of the cell entirely.
Similar to a cellular post office, the Golgi apparatus is larger in cells that produce and secrete significant amounts of proteins. It works in conjunction with the rough ER, ribosomes, and nucleus, each playing an essential role in the synthesis and handling of proteins within the endomembrane system.