Question

explain how a typical digestive enzyme is secreted starting from the time the ribosome starts translating the mRNA of the gene encoding the digestive enzyme

Answer 1

the ribosome in the cytosol starts to translate the mRNA and once it translates the signal sequence, signal recognition particle(SRP) binds to the signal sequence, then translation pauses then SRP replaces the bound GDP with GTP and then SRP binds to SRP receptor on the ER membrane, then it hydrolyzes the GTP to GDP and uses the energy to load the mRNA-ribosome-signal sequence complex to the translocon on the ER membrane, then translation begins, and protein is synthesized into the ER lumen, then signal peptidase in the ER lumen cleaves the signal sequence as the signal sequence enters the ER lumen, translated protein is folded in the ER lumen, then packed into vesicles, these vesicles carry protein to the Golgi-apparatus, at the Golgi-apparatus protein is modified, if required and the packed into vesicles, these vesicles fuse with the plasma membrane and release protein to the extracellular space.

digestive enzymes are secreted by pancreatic cells, are collected on the  pancreatic duct carries.