AIIMS CRE, SNO-2024: Which of the following is considered a macromolecule?

AIIMS CRE, SNO-2024

Biochemistry & Nutrition

Easy

Appeared in: AIIMS CRE, SNO-2024

Explanation

Proteins are one of the four major classes of biological macromolecules.
They are large, complex polymers made up of smaller monomer units called amino acids, linked together in long chains.
Their large size and complex three-dimensional structures are critical for their diverse functions, including enzymatic activity, structural support, and transport.

Option A: Glucose is a monosaccharide, which is a simple sugar. It is a monomer, or a building block, for larger carbohydrate macromolecules like starch and glycogen, but it is not a macromolecule itself.
Option B: Water (H₂O) is a small, simple inorganic molecule. While essential for life, it does not fit the definition of a macromolecule, which are large organic polymers.
Option D: Sodium chloride (NaCl) is an inorganic salt. It is a small ionic compound that dissociates into ions in water and is not a large, complex organic polymer.

Visual 1: Diagram - Illustrating the four major classes of biological macromolecules (proteins, carbohydrates, lipids, nucleic acids) and their corresponding monomer building blocks. This helps visualize the concept of polymers being built from monomers.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of biological macromolecules as background academic context rather than a clinical decision trigger.
Understanding macromolecules is fundamental to nursing as they are the basis of nutrition, physiology, and pathology.
Proteins, for example, function as enzymes, hormones (insulin), transport molecules (hemoglobin), and antibodies. Assessing a patient's protein status (e.g., serum albumin levels) is crucial for evaluating nutritional status and wound healing capacity.
What if? - If a patient has severe protein-calorie malnutrition (Kwashiorkor), they will have low levels of plasma proteins like albumin. This leads to a decrease in plasma oncotic pressure, causing fluid to shift from the blood vessels into the interstitial tissue, resulting in generalized edema.

How to Approach the Question

First, understand the definition of the keyword 'macromolecule'. It refers to a very large molecule, typically a polymer, such as a protein or nucleic acid.
Next, evaluate each option against this definition.
Analyze Option A (Glucose): Recall that glucose is a simple sugar (monosaccharide), which is a building block (monomer), not a large polymer.
Analyze Option B (Water): Recognize that water (H₂O) is a very small, simple inorganic molecule.
Analyze Option C (Protein): Identify that proteins are long chains of amino acids, making them large polymers, which fits the definition of a macromolecule.
Analyze Option D (Sodium Chloride): Know that sodium chloride (NaCl) is a simple inorganic salt, not a large organic polymer.

Concept Tested & Keywords

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Textbook of Biochemistry for Medical Students 6th Edition — DM Vasudevan p. 320-560