Final answer:
The Golgi apparatus adds sugar molecules to proteins and lipids through a process called glycosylation as they travel through the endomembrane system. These modified molecules are then tagged to be sorted and sent to their correct destinations.
Step-by-step explanation:
The Golgi apparatus is responsible for processing proteins and lipids, and one of the modifications that occurs is the addition of sugar molecules to these molecules. This process is known as glycosylation and it starts in the rough endoplasmic reticulum (RER). Glycoproteins are synthesized as core glycosides in the RER, and as they travel through the Golgi vesicles, more sugars are added to complete the glycoprotein synthesis. These modified proteins and lipids are then tagged with phosphate groups or other small molecules to be sorted and directed to their proper destinations.