Final answer:
Proteins are initially decorated with an oligosaccharide tree on asparagine residues in the rough endoplasmic reticulum (RER) of the cell. Glycoprotein synthesis begins in the RER and continues in the Golgi apparatus.
Step-by-step explanation:
The proteins are initially decorated with an oligosaccharide tree on asparagine residues in the rough endoplasmic reticulum (RER) of the cell. This is where glycoprotein synthesis begins and a core glycoside is created. The proteins then travel through the Golgi apparatus of the endomembrane system, where terminal glycosylation attaches more sugars to complete the glycoprotein synthesis.