Problem 103 - Objective Biology for NEET

Question

Trypsinogen is activated by (a) Enterokinase (b) Chymotrypsin (c) Rennin (d) Acidic pH

Step-by-Step Solution

Answer

The correct answer is (a) Enterokinase, as it activates trypsinogen.

Step 1: Understanding Trypsinogen

Trypsinogen is a zymogen (inactive enzyme) produced by the pancreas. Pancreatic enzymes are usually produced in an inactive form to prevent autodigestion of the pancreas.

Step 2: Understanding Activation Process

Like all other zymogens, trypsinogen requires activation to become a functional enzyme. This activation process is done by another enzyme.

Step 3: Identifying the Activating Enzyme

Of the options given, we know that Enterokinase, an enzyme located on the mucosal surface cells of the duodenum (small intestine segment), activates trypsinogen into trypsin.

Key Concepts

Trypsinogen

Trypsinogen is a key player in the digestion process and serves as a precursor, or inactive form, of the enzyme trypsin. It's a type of zymogen—a group of inactive enzymes that need to be activated before they can perform their enzymatic functions.
This clever mechanism of producing enzymes in an inactive form helps to prevent potential damage to the organs that produce them. In the case of trypsinogen, it is produced in the pancreas, which is an organ that secretes several digestive enzymes.
These enzymes are crucial for breaking down proteins in the diet. However, if they were active inside the pancreas, they could start digesting the pancreatic tissue itself, leading to dangerous conditions like pancreatitis. By releasing trypsinogen instead of active trypsin, the body ensures that protein digestion happens only once the enzyme reaches the intestinal tract, where it is needed.

Enterokinase

Enterokinase, sometimes referred to as enteropeptidase, is an enzyme with a specialized role in digestion. It resides in the duodenum, which is the first part of the small intestine, and it has a crucial function for activating trypsinogen.
When food reaches the duodenum, enterokinase works by cleaving a specific peptide bond in trypsinogen to convert it into trypsin. This transformation is essential because trypsin is the active form that performs proteolysis—breaking down proteins into smaller peptides and amino acids—essential for normal digestion.

• Location: The duodenum, attached to the mucosal lining.
• Function: Activates trypsinogen to trypsin.

Interestingly, the activation of trypsinogen by enterokinase also initiates a cascade where activated trypsin can then activate other zymogens, amplifying the digestive process. This highlights enterokinase's pivotal role in the regulation and efficiency of our digestive system.

Pancreatic Enzymes

Pancreatic enzymes are a group of powerful enzymes secreted by the pancreas and play an essential role in digestion. They are crucial for breaking down the food we eat into nutrients that the body can readily absorb.
These enzymes include trypsinogen, amylase, lipase, and others. Most of them are secreted in their inactive forms or precursors, known as zymogens, which get activated once they reach the intestinal lumen.

• Trypsinogen - becomes trypsin, digesting proteins.
• Amylase - breaks down carbohydrates into sugars.
• Lipase - works on fats to break them into fatty acids and glycerol.

This method of enzyme production and activation prevents damage to the pancreatic tissue, ensuring enzymes only become active in the small intestine where digestion should happen. The coordination of pancreatic enzymes reflects the body's efficient way of managing enzyme activity to optimize digestion while protecting delicate tissues.