Final answer:
Peptide hormones are converted from preprohormones by being synthesized as preprohormones with a signal peptide, processed in the rough endoplasmic reticulum (RER) where the signal peptide is cleaved, and then further modified in the Golgi apparatus before being packaged into vesicles for distribution.
Step-by-step explanation:
Peptide hormones are converted from preprohormones through a series of steps that involve synthesis, modification, and packaging in different cellular compartments. Initially, peptide hormones are synthesized as larger preprohormones, which include a signal peptide. These preprohormones are synthesized by ribosomes and directed into the rough endoplasmic reticulum (RER), where the signal peptide is cleaved, creating prohormones.
The prohormones then travel to the Golgi apparatus where they undergo further processing, which can include the cleavage of additional peptide segments, folding, and addition of carbohydrate groups if necessary. The packaged and fully modified hormones are then tagged in the vesicle for specific destinations such as secretion outside of the cell.
This processing sequence typically follows the pathway: synthesis of the protein on the ribosome, modification in the endoplasmic reticulum, tagging in the Golgi, and distribution via the vesicle. The correct answer to the student's question, "How are peptide hormones converted from preprohormones?" would be (a) Cleavage in the endoplasmic reticulum.