Which organelle is involved in the modification and packaging of proteins?

The Golgi apparatus plays a crucial role in the modification and packaging of proteins. After proteins are synthesized in the endoplasmic reticulum, they are transported to the Golgi apparatus, where they undergo further processing. This includes the addition of carbohydrate groups (glycosylation), the folding into their functional shapes, and sorting for delivery to their final destinations, which could be lysosomes, the cell membrane, or secretion outside the cell.

The Golgi apparatus consists of a series of flattened, membrane-bound sacs, called cisternae, which allow for sequential modification and compartmentalization of proteins. Once the proteins are properly modified, they are packaged into vesicles that transport them to their appropriate locations. This organelle is essential for facilitating the post-translational modifications required for proteins to function correctly.

In contrast, the nucleus is primarily involved in the storage of genetic material and the synthesis of messenger RNA, while mitochondria are focused on energy production through cellular respiration. The endoplasmic reticulum is responsible for the initial synthesis of proteins, but it is the Golgi apparatus that specializes in their final modification and packaging before distribution.