Question

In the stomach, curdling of milk is due to the action of

• A. Pepsin
• B. Rennin
• C. HCI
• D. Renin

Answer 1

The correct option is B Rennin

Chymosin is known as rennin, is a proteolytic enzyme synthesized by chief cells in the stomach. Its role in digestion is to curdle or coagulate milk in the stomach, a process of considerable importance in the very young animal. If milk were not coagulated, it would rapidly flow through the stomach and miss the opportunity for initial digestion of its proteins.

Chymosin efficiently converts liquid milk to a semisolid like cottage cheese, allowing it to be retained for longer periods in the stomach. Chymosin secretion is maximal during the first few days after birth, and declines thereafter, replaced in effect by secretion of pepsin as the major gastric protease.

Chymosin is secreted as an inactive proenzyme called prochymosin that, like pepsin, is activated on exposure to acid. Chymosin is also similar to pepsin in being most active in acidic environments, which makes sense considering its mission.