Question

Zymogenic cells of gastric glands secrete
a) Pepsinogen
b) Trypsin
c) Pepsin
d) Chymotrypsin

Answer 1

Hint : Zymogenic cells are also known as gastric chief cells or peptic cells. The gland which is secreted is powerful and abundant protein digestive enzyme.

Complete answer : Zymogenic cells of gastric glands secrete Pepsinogen. Pepsinogen is secreted by the gastric chief cells as a proenzyme and then converted by the gastric lumen to the active enzyme pepsin. Zymogenic cells are epithelial cells which are found within the gastric unit or gastric gland. They form the base of the gastric unit. They also contain many large secretory vesicles filled with digestive enzymes in the apical cytoplasm. Pepsinogens consists of single polypeptide chains with a molecular weight of approximately 42000 Da. Pepsinogens are the zymogen or inactive precursor of pepsin, the principal proteolytic enzyme of gastric juice. Pepsinogen was first crystallized from the gastric mucosa of swine and several pepsinogens have now been separated.

Additional information.

Trypsin is the enzyme which is produced by the pancreas in an inactive form which is known as trypsinogen.
Pepsin is the endopeptidase which is produced or secreted in the chief cells of the stomach lining and it is the main digestive enzyme.
Chymotrypsin is a digestive protease which is secreted by pancreatic acinar cells.
As the other 3 enzymes are not secreted by zymogenic cells gastric glands that is why they can’t be considered as the answer.

Thus, the correct option is A i.e., Pepsinogens.

Note : The role of pepsin and its pre-cursor in protein digestion was first described in the 19th century. Pepsinogens belong to the endopeptidase family of aspartic proteinases. The aspartic proteinases are also called as acid proteinases because they act between pH 1.5 and 5.