Final answer:
Proteins synthesized on the ribosomes of the Rough Endoplasmic Reticulum (ER) are transported to the Golgi apparatus where they are modified, sorted, and packaged for delivery inside or outside the cell.
Step-by-step explanation:
Before proteins go through the Golgi apparatus, they first pass through the Rough Endoplasmic Reticulum (ER). This is where proteins are synthesized on ribosomes and then enter the ER lumen or become part of the RER membrane. The proteins are then packaged into transport vesicles which fuse with the Golgi apparatus on its receiving face. Inside the Golgi apparatus, the proteins undergo further modifications, sorting, and packaging. They are tagged to ensure they reach the correct cellular destinations and may be organized into lysosomes or transported to other areas of the cell. Any proteins destined to leave the cell will be exported through exocytosis. The Golgi apparatus acts like a cellular 'post office', processing, and routing products to their final destinations.