What is the Golgi apparatus, and how does it function in protein modification and sorting?

The Golgi apparatus is an organelle that modifies and sorts proteins in eukaryotic cells.

The Golgi apparatus is a flattened stack of membrane-bound sacs found in eukaryotic cells. It is responsible for modifying, sorting, and packaging proteins and lipids that have been synthesized in the endoplasmic reticulum (ER). The Golgi apparatus consists of three main regions: the cis-Golgi, medial-Golgi, and trans-Golgi. Proteins enter the Golgi at the cis-Golgi and are modified as they move through the different regions.

The Golgi modifies proteins by adding or removing carbohydrate chains, phosphorylating or sulfating amino acids, and cleaving off signal sequences. These modifications can alter the function, stability, and localization of the protein. The Golgi also sorts proteins based on their final destination. Proteins that are destined for secretion are packaged into vesicles and transported to the plasma membrane. Proteins that are destined for lysosomes are packaged into vesicles and transported to the endosome, where they are further sorted and delivered to the lysosome.

In summary, the Golgi apparatus is an essential organelle that modifies and sorts proteins in eukaryotic cells. Its ability to modify and sort proteins is crucial for maintaining cellular function and homeostasis.