Final answer:
The appropriate order of locations through which a protein destined for the plasma membrane travels is from the ER to the Golgi apparatus, and then to the plasma membrane. Choice (d) ER → Golgi → plasma membrane is the correct sequence.
Step-by-step explanation:
In the process of protein synthesis and transportation to the plasma membrane, proteins follow a specific pathway through the cell. The correct order is: ER (endoplasmic reticulum) → Golgi apparatus → plasma membrane. Initially, proteins are synthesized on ribosomes associated with the ER. They enter the ER lumen where they undergo folding and modification. Then, they are transported to the Golgi apparatus via vesicles where they are further modified, packaged, and tagged for their final destination.
The Golgi apparatus has a receiving face (cis face) where it receives the proteins from the ER and an outgoing face (trans face) from which it sends the processed proteins to the plasma membrane or other organelles. Finally, vesicles containing the fully processed proteins fuse with the plasma membrane, inserting the proteins into the membrane or releasing them outside the cell. Therefore, the correct choice that reflects the appropriate order of locations a protein travels to reach the plasma membrane is (d) ER → Golgi → plasma membrane.