Endoplasmic reticulum (C), Golgi bodies (B), Post-Golgi vesicles (D), Plasma membrane (A)
Work Step by Step
Proteins are synthesized at ribosomes. Ribosomes can be free-floating or attached to the endoplasmic reticulum (this is called the rough ER). If the protein that is made is one that needs to be exported out of the cell then it will follow the pathway described above. Proteins that do not need to be exported out will not follow this pathway.