What is the primary role of the Golgi apparatus in a cell?

The primary role of the Golgi apparatus in a cell is the modification of lipids and proteins. Once proteins and lipids are synthesized in the endoplasmic reticulum (ER), they are transported to the Golgi apparatus, where they undergo further processing. This processing often includes the addition of carbohydrates (glycosylation), phosphorylation, and sulfation, which are critical for the proteins' final functionality. The Golgi apparatus then sorts and packages these modified molecules into vesicles that are destined for different locations within the cell or for secretion outside the cell. This functional distinction makes the Golgi apparatus a central hub in the cellular machinery responsible for managing and directing the flow of biochemical products.