Problem 29 - Chemistry in 30 days

Question

Campleie hydrolysis of cellolose gives (a) L-glucuse (b) D-fructase (c) D-ribese (d) D-glucase

Step-by-Step Solution

Answer

Complete hydrolysis of cellulose gives (d) D-glucose.

Step 1: Understand Cellulose Composition

Cellulose is a polysaccharide consisting of a linear chain of several hundred to over ten thousand β-D-glucose units. Hence, when it undergoes complete hydrolysis, the products will reflect its monomeric units.

Step 2: Hydrolysis Reaction of Cellulose

Hydrolysis of cellulose means breaking down the glycosidic bonds between β-D-glucose units by the addition of water.

Step 3: Identify the Product of Hydrolysis

Since cellulose is composed of β-D-glucose units, the hydrolysis will yield D-glucose as the product.

Step 4: Match the Product with Given Options

Among the given options, (d) D-glucase matches as the correct representation of the hydrolysis product. Glucose from cellulose is in the D-form.

Key Concepts

D-glucose

D-glucose is a simple sugar and one of the most common monosaccharides found in nature. It is the building block of many carbohydrates and plays a crucial role in biology.

• Structure: D-glucose is a hexose, which means it has six carbon atoms. It features a characteristic aldehyde group at one end, making it an aldose.
• Function: This sugar is vital for energy. In humans and other organisms, it is a primary source of energy, often released during cellular respiration.

D-glucose is the monomeric unit that forms larger carbohydrate structures like cellulose by linking in long chains. Its importance cannot be overstated, as it fuels many biological processes.

polysaccharide

Polysaccharides are complex carbohydrates composed of long chains of monosaccharide units linked together. They play various roles in biological systems, serving as energy sources and structural components.

• Components: A polysaccharide is made up of monosaccharides, which are simple sugars like glucose. In cellulose, the monosaccharide is β-D-glucose.
• Functions: In nature, polysaccharides function as energy reserves (e.g., starch in plants) and structural materials (e.g., cellulose in plant cell walls).

Cellulose, a notable polysaccharide, consists of many D-glucose units bonded in a specific fashion, providing rigidity to plant structures.

glycosidic bonds

Glycosidic bonds are covalent links between carbohydrate molecules. They form when a hydroxyl (-OH) group of one sugar molecule binds with an anomeric carbon of another.

• Formation: These bonds result from a dehydration reaction, where a water molecule is released when two sugar molecules join.
• Types: Depending on the involved carbon atoms and orientation, they can be α or β bonds. Cellulose contains β-1,4-glycosidic bonds, sustaining its structural integrity.

In cellulose, glycosidic bonds link β-D-glucose units in a straight chain, contributing to its high tensile strength and resistance to enzymatic degradation.

monomeric units

Monomeric units are the basic building blocks of polymers. In the context of biology and chemistry, they refer to individual molecules that join to form more complex structures.

• Polymers: These include natural polymers such as proteins, nucleic acids, and polysaccharides.
• Cellulose: In cellulose, the monomeric unit is β-D-glucose. It is repeated in a large sequence, forming an extensive, stable structure.

Understanding these basic units is crucial since the properties of a polymer depend on the nature and arrangement of its monomers. In cellulose, the specific arrangement of D-glucose units allows it to serve its function in plant cell walls efficiently.