Problem 76 - A Complete Resource Book in Chemistry for JEE Main

Question

Maximum number of monosaccharide units present in oligosaccharides is (a) 5 (b) 10 (c) 15 (d) 20

Step-by-Step Solution

Answer

The maximum number of monosaccharide units in oligosaccharides is 10.

Step 1: Understanding Oligosaccharides

Oligosaccharides are carbohydrates formed by a small number of monosaccharide units. They are larger than disaccharides but have fewer monosaccharide units than polysaccharides.

Step 2: General Definition of Oligosaccharides

In biochemical terms, oligosaccharides are generally composed of 2 to 10 monosaccharide units. Beyond this, they are classified as polysaccharides.

Step 3: Identifying the Maximum Limit

Based on their definition, the maximum number of monomer units in oligosaccharides is typically 10, as more than 10 units classify as polysaccharides.

Step 4: Choosing the Correct Option

Cross-reference the understanding with the given options: (a) 5, (b) 10, (c) 15, (d) 20, and select the correct answer, which is 10.

Key Concepts

Monosaccharide Units

In the world of carbohydrates, monosaccharide units form the basic building blocks. Think of monosaccharides as the individual bricks in a wall; they are the simplest form of carbohydrates. They consist of a single sugar molecule, such as glucose or fructose. These simple sugars can be connected together to form more complex carbohydrates.

Each monosaccharide has a unique structure, with typically 3 to 7 carbon atoms. When these small molecules join together, they form larger carbohydrate structures, like disaccharides (two monosaccharides), oligosaccharides, and eventually polysaccharides.

It's important to know that oligosaccharides, which we'll discuss next, comprise between 2 to 10 of these monosaccharide units. As you move to larger structures, the complexity and function of the carbohydrate can change significantly.

Polysaccharides

Polysaccharides are essentially the giants of the carbohydrate world. When more than 10 monosaccharide units link together, they form polysaccharides. Unlike oligosaccharides, polysaccharides can contain hundreds or even thousands of monosaccharide units.

Some common examples of polysaccharides include starch, cellulose, and glycogen. These molecules are crucial in both plant and animal biology. For instance, starch acts as a storage form of energy in plants while glycogen serves a similar function in animals. Addtionally, cellulose provides structural integrity to plant cell walls.

The properties of polysaccharides, such as their solubility and digestibility, can vary greatly depending on their structure and composition. This makes them vital in a variety of biological processes and applications.

Biochemical Classification

In biochemistry, carbohydrates are classified based on the number of monosaccharide units they contain. This classification is important because it helps us understand their function and role in living organisms.

- **Monosaccharides**: As mentioned, these are the simplest form, like glucose. - **Disaccharides**: These contain two monosaccharide units, such as sucrose (table sugar). - **Oligosaccharides**: These range from 2 to 10 monosaccharide units and play a crucial role in cellular processes such as cell recognition and signaling. - **Polysaccharides**: Containing over 10 units, they are involved in storage and structural integrity of biological systems.

This hierarchical classification helps in defining the characteristics and functions of different carbohydrates. It also provides a framework for scientists and students alike to study and understand biological processes where these carbohydrates are involved.