Lactose is made up of?

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

Lactose is a disaccharide, meaning it is composed of two simple sugar (monosaccharide) units.
Specifically, lactose is formed by the chemical bonding of one glucose molecule and one galactose molecule.
It is primarily found in milk and dairy products, which is why it's often called 'milk sugar'.
The enzyme lactase is required to hydrolyze (break down) lactose into glucose and galactose for absorption by the body.

Option B: Glucose is a monosaccharide and only one of the two components of lactose. Lactose is a disaccharide and requires two monosaccharide units.
Option C: The combination of glucose and fructose forms sucrose, which is commonly known as table sugar or cane sugar.
Option D: Fructose is a monosaccharide, often called fruit sugar. It is a component of sucrose, but not lactose.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Biochemistry of Carbohydrates: Disaccharide Composition as background academic context rather than a clinical decision trigger.
Understanding the composition of lactose is fundamental for nurses to grasp the pathophysiology of lactose intolerance.
Lactose intolerance results from a deficiency of the enzyme lactase, which is necessary to split lactose into glucose and galactose for absorption.
Nurses can educate patients with lactose intolerance on reading food labels for hidden sources of lactose and suggest alternatives like lactose-free milk or lactase enzyme supplements.

How to Approach the Question

First, identify the key term in the question: 'Lactose'.
Recall the basic classifications of carbohydrates: monosaccharides (single sugars), disaccharides (two sugars), and polysaccharides (many sugars).
Recognize that lactose is a disaccharide.
Access your memory of the three main dietary disaccharides and their components:
Lactose = Glucose + Galactose
Sucrose = Glucose + Fructose

Concept Tested & Keywords

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E6 Nutrition Monika Sharma 3e p. 63-65

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 75-77

Practise the full JODHPUR AIIMS SNO-2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.