Name two key brush-border enzymes and their roles in carbohydrate digestion.

Name two key brush-border enzymes and their roles in carbohydrate digestion.

• A. Lipase and Amylase digest lipids and starch.
• B. Lactase and Maltase hydrolyze disaccharides to monosaccharides.
• C. Peptidases digest peptides.
• D. Nucleases digest nucleic acids.

Answer: (B)

The key idea is that digestion of carbohydrates at the small-intestinal brush border relies on enzymes located on the microvilli that finish converting disaccharides into absorbable monosaccharides. Lactase and maltase are classic examples of these brush-border enzymes. Lactase splits lactose into glucose and galactose, while maltase breaks maltose down into two glucose molecules. This step is crucial because monosaccharides are the forms that can be transported into enterocytes for absorption into the bloodstream. Understanding their role also highlights why this pair fits best: these enzymes directly act on disaccharides produced from earlier carbohydrate digestion and prepare them for absorption. Other enzymes listed serve different purposes—lipase digests fats, amylase digests starch but is not a brush-border enzyme, peptidases digest proteins, and nucleases digest nucleic acids—so they don’t describe the brush-border disaccharidase activity essential for carbohydrate absorption.

The key idea is that digestion of carbohydrates at the small-intestinal brush border relies on enzymes located on the microvilli that finish converting disaccharides into absorbable monosaccharides. Lactase and maltase are classic examples of these brush-border enzymes. Lactase splits lactose into glucose and galactose, while maltase breaks maltose down into two glucose molecules. This step is crucial because monosaccharides are the forms that can be transported into enterocytes for absorption into the bloodstream.

Understanding their role also highlights why this pair fits best: these enzymes directly act on disaccharides produced from earlier carbohydrate digestion and prepare them for absorption. Other enzymes listed serve different purposes—lipase digests fats, amylase digests starch but is not a brush-border enzyme, peptidases digest proteins, and nucleases digest nucleic acids—so they don’t describe the brush-border disaccharidase activity essential for carbohydrate absorption.