Problem 62 - Arihant Objective Approach to Organic Chemistry for IIT JEE and NEET all Medical Entrances Part 4

Question

Which of the following is oligosaccharide? (a) Maltose (b) Sucrose (c) Both (a) and (b) (d) None of these

Step-by-Step Solution

Answer

(d) None of these

Step 1: Understand the definition of an oligosaccharide

An oligosaccharide is a carbohydrate whose molecules are composed of a small number (typically 3 to 10) of simple sugars (monosaccharides). Oligosaccharides differ from disaccharides, which consist of only two sugar units.

Step 2: Identify the components of Maltose

Maltose is a disaccharide, consisting of two glucose units connected by a glycosidic bond. Since it contains only two sugar units, it does not qualify as an oligosaccharide.

Step 3: Identify the components of Sucrose

Sucrose is also a disaccharide, composed of one glucose molecule and one fructose molecule linked together. Similar to maltose, having only two monosaccharides, it is not classified as an oligosaccharide.

Step 4: Determine if both (a) and (b) are oligosaccharides

Since neither maltose nor sucrose is classified as an oligosaccharide, the option 'both (a) and (b)' is not correct.

Step 5: Choose the correct answer

Given that neither maltose nor sucrose fits the definition of an oligosaccharide, the correct answer is 'None of these'.

Key Concepts

Carbohydrates

Carbohydrates are one of the essential biomolecules found in living organisms. They are made up of carbon, hydrogen, and oxygen atoms, typically in the ratio of 1:2:1. Carbohydrates are categorized into three main groups based on the number of sugar units they contain:

• Monosaccharides: These are simple sugars with a single sugar unit. Examples include glucose and fructose.
• Disaccharides: Comprised of two sugar units, maltose and sucrose fall under this category.
• Oligosaccharides: These consist of a small number (3 to 10) of monosaccharide units bound together.
• Polysaccharides: Large molecules with many sugar units, such as starch and cellulose.

Carbohydrates play vital roles in providing energy, structural functions, and other biological processes.

Disaccharides

Disaccharides are carbohydrates consisting of two monosaccharide units. These units are linked together through a glycosidic bond. Two of the most common disaccharides are maltose and sucrose.

• Maltose: Composed of two glucose molecules. It is often found in grains and is a result of the breakdown of starch.
• Sucrose: Formed by combining glucose and fructose. It's the common table sugar used in households.
  Disaccharides are an essential source of energy. Once ingested, they are broken down into monosaccharides during digestion, making them ready for absorption and metabolism.

Monosaccharides

Monosaccharides are the simplest form of carbohydrates. They cannot be broken down into simpler sugars. Some well-known monosaccharides include glucose, fructose, and galactose.

• Glucose: The most common monosaccharide, often referred to as blood sugar.
  It is vital for cellular respiration and a primary energy source for the body.
• Fructose: Found in fruits, it's the sweetest of all natural sugars.
• Galactose: Although less common on its own, it's part of the disaccharide lactose, found in milk.

Monosaccharides are crucial to cellular metabolism as they provide immediate energy and also play key roles in building other carbohydrates.