What is the primary function of the Golgi apparatus?

The Golgi apparatus plays a crucial role in the post-translational modification, sorting, and packaging of proteins that have been synthesized in the endoplasmic reticulum. Once proteins are synthesized, they are transported to the Golgi apparatus, where they undergo various modifications, such as glycosylation or phosphorylation. This is essential for their proper functioning and signaling.

After modifications, the Golgi apparatus sorts these proteins based on their destinations—either for secretion outside the cell or for delivery to various organelles within the cell. This sorting is vital for maintaining cellular organization and function, ensuring that proteins reach their correct locations to perform their roles efficiently. Therefore, this choice clearly aligns with the primary function of the Golgi apparatus in cellular biology.