Question

question 2
0.5 pts
which of the following correctly describes the pathway taken by a protein destined for secretion from an animal cell?
○ rough er → transport vesicle → golgi → transport vesicle → plasma membrane
○ rough er → transport vesicle → lysosome → transport vesicle → plasma membrane
○ golgi → rough er → transport vesicle → plasma membrane
○ rough er → transport vesicle → golgi → transport vesicle → lysosome → plasma membrane
○ plasma membrane → transport vesicle → golgi → transport vesicle → rough er

Explanation:

Secretory proteins are first synthesized on the rough endoplasmic reticulum (rough ER). They are then packaged into transport vesicles that deliver them to the Golgi apparatus for processing. After modification, the proteins are again packaged into transport vesicles that fuse with the plasma membrane to release the protein outside the cell. Lysosomes are involved in intracellular digestion, not secretion, so pathways including lysosomes are incorrect. The sequence must start at the rough ER, not the Golgi or plasma membrane.

Answer:

A. rough ER $
ightarrow$ transport vesicle $
ightarrow$ Golgi $
ightarrow$ transport vesicle $
ightarrow$ plasma membrane