Which cell part is involved in modifying, sorting, and packaging proteins?

The Golgi apparatus is the organelle responsible for modifying, sorting, and packaging proteins for secretion or use within the cell. After proteins are synthesized by ribosomes on the rough endoplasmic reticulum, they are transported to the Golgi apparatus. Here, the proteins undergo various modifications, such as the addition of carbohydrate groups (glycosylation) or phosphorylation.

Once these modifications are complete, the Golgi apparatus sorts the proteins based on their destinations, packaging them into vesicles. These vesicles then transport the proteins to their appropriate locations, which may include outside the cell (via exocytosis) or to different organelles within the cell.

The rough endoplasmic reticulum is primarily involved in the synthesis of proteins rather than their modification or sorting. Lysosomes are organelles that contain enzymes for breaking down waste materials and cellular debris. The nucleus contains the genetic material of the cell and is involved in the processes of transcription and replication, not in protein modification or packaging. Hence, the role of the Golgi apparatus is essential and distinct in the pathway of protein transport and processing within the cell.