What role does the Golgi apparatus play in the cell?

The Golgi apparatus is primarily responsible for the modification, sorting, and packaging of proteins and lipids that have been synthesized in the endoplasmic reticulum. Once proteins are created in the rough endoplasmic reticulum, they are transported to the Golgi apparatus, where they undergo various modifications, such as glycosylation, phosphorylation, or sulfation. These modifications are crucial for the proteins to function correctly and are vital for their transport to specific destinations within or outside the cell.

After these modifications, the Golgi apparatus packages the proteins into vesicles. These vesicles then transport the modified proteins to different parts of the cell, such as lysosomes or the plasma membrane, or they may be secreted out of the cell. This role is essential for maintaining cellular function and ensuring that proteins reach their correct locations, which is why the Golgi apparatus is often referred to as the cell's "post office."

The other options involve processes that are not related to the primary function of the Golgi apparatus. DNA replication occurs in the nucleus, energy production involves the mitochondria, and cellular respiration is a broad metabolic process that occurs throughout the cell but is not a function of the Golgi apparatus itself.