2.b.iv. The Secretory Pathway

Question 1

describe the secretory pathway

Answer 1

proteins for secretion are translated in ribosomes in the RER and enter its lumen. vesicles transport the proteins through the Golgi apparatus and the golgi apparatus packages them into secretory vesicles. these vesicles move to and fuse with the plasma membrane, releasing the proteins outside of the cell.

Question 2

give some examples of secreted proteins

Answer 2

digestive enzymes, peptide hormones

Question 3

many secreted proteins are released as ____ ____

Answer 3

inactive precursors which require proteolytic cleavage to become active

Question 4

describe how inactive precursors become active

Answer 4

proteolytic cleavage - a post-translational modification which involves removing some of the protein to allow its final active conformation to be to be formed

Question 5

give an example of proteins which undergo proteolytic cleavage

Answer 5

digestive enzymes. an active form inside a cell would be damaging and so it is activated at the site of action