Question

The pathway for a protein destined for incorporation into the plasma membrane would be ____.

1) nuclear ribosome → nuclear pore → cytoplasm
2) nucleus → mitochondria → plasmodesmata
3) rough ER → Golgi body → exocytotic vesicle
4) smooth ER → rough ER → chloroplast
5) lysosome → rough ER → vesicle

Answer 1

The pathway for a protein destined for incorporation into the plasma membrane would be 3) rough ER → Golgi body → exocytotic vesicle

Step-by-step explanation:

This is because the rough endoplasmic reticulum (ER) is responsible for the synthesis of membrane and secretory proteins. Ribosomes on the surface of the rough ER produce these proteins, which then get embedded in its membrane. The rough ER then packages the proteins into transport vesicles.

These vesicles then fuse with the cis face of the Golgi apparatus. In the Golgi apparatus, the proteins are further modified and sorted. After their synthesis is complete, they exit as integral membrane proteins in vesicles that bud from the trans face of the Golgi apparatus.

Finally, these vesicles fuse with the plasma membrane, incorporating the proteins into the plasma membrane of the cell. Therefore the correct answer is 3) rough ER → Golgi body → exocytotic vesicle