**Question:** The brush border bound hydrolase linked with sucrase is

A. maltase
B. lactase
C. isomaltase
D. cellobiosidase

**Correct Answer:** C. isomaltase

**Core Concept:**
Brush border hydrolases are enzymes located in the brush border membrane of the small intestine, particularly in the jejunum and ileum. These enzymes help in the digestion and absorption of carbohydrates, particularly disaccharides. Sucrase is one such enzyme that is involved in the hydrolysis of sucrose (table sugar) into its constituent monosaccharides, glucose and fructose.

**Why the Correct Answer is Right:**
Isomaltase is a hydrolase enzyme that is specifically linked to sucrase in the brush border membrane of the small intestine. It is responsible for the hydrolysis of isomaltose, a disaccharide, into its constituent monosaccharides, glucose and galactose. Since isomaltase is linked to sucrase, it is present in the same membrane as sucrase and shares its function in carbohydrate digestion.

**Why Each Wrong Option is Incorrect:**

A. Maltase (linked to maltase) is responsible for the hydrolysis of maltose into glucose and galactose. It is not linked to sucrase, making it an incorrect option.
B. Lactase (linked to lactase) is responsible for the hydrolysis of lactose into glucose and galactose. It is also not linked to sucrase.
D. Cellobiosidase (linked to cellobiosidase) is responsible for the hydrolysis of cellobiose into glucose and galactose. Like maltase and lactase, it is not linked to sucrase either.

**Clinical Pearl:**
The correct carbohydrate digestion pathways are essential for understanding the absorption of various sugars in the small intestine. Knowledge of these enzymes and their functions is crucial for clinical practice, as it helps in understanding various nutritional deficiencies and their management strategies. Additionally, understanding carbohydrate digestion is fundamental for assessing and diagnosing malabsorption syndromes, such as lactase deficiency, which can lead to lactose intolerance, a common condition affecting the digestion and absorption of lactose in the small intestine.

**Why Each Wrong Option is Incorrect:**
Option A (maltase) and Option B (lactase) are incorrect because they are linked to their respective hydrolases (maltase for maltose and lactase for lactose). Understanding the correct enzymes and their functions is essential for understanding the malabsorption syndromes and their management strategies.

Option D (cellobiosidase) is incorrect as it is linked to cellobiosidase, which hydrolyzes cellobiose into glucose and galactose, not sucrase.

**Why the Correct Answer is Right:**
Option C (isomaltase) is correct because isomaltase is linked to sucrase, which hydrolyzes isomaltose into glucose and fructose. Since isomaltase is linked to