Understand the concept of the endomembrane system: The endomembrane system is a group of interconnected organelles in eukaryotic cells that work together to modify, package, and transport proteins and lipids. Key components include the rough endoplasmic reticulum (RER), Golgi apparatus, lysosomes, and the plasma membrane.
Recognize the role of the rough endoplasmic reticulum (RER): Proteins destined for secretion are synthesized by ribosomes attached to the RER. These proteins are folded and undergo initial modifications, such as glycosylation, within the RER.
Learn the function of the Golgi apparatus: After being synthesized and modified in the RER, proteins are transported to the Golgi apparatus via vesicles. The Golgi apparatus further modifies, sorts, and packages these proteins for their final destination.
Understand the final step of secretion: Proteins packaged in vesicles from the Golgi apparatus are transported to the plasma membrane. The vesicles fuse with the plasma membrane, releasing the proteins outside the cell via exocytosis.
Eliminate incorrect pathways: Based on the roles of the organelles, the correct pathway for protein secretion is 'Rough endoplasmic reticulum → Golgi apparatus → plasma membrane.' Other options, such as involving mitochondria or lysosomes, do not align with the protein secretion process.