Comprehension

Carbohydrates are the major components of all living organisms. Sugars are carbohydrates. The major types of sugars include monosaccharides and disaccharides. The main difference between monosaccharides, disaccharides and polysaccharides is that monosaccharides are monomer of sugars and disaccharides are composed of two monomers, whereas polysaccharides are composed of a large number of monomers. Monosaccharides are single sugar molecules which act as the building blocks of disaccharides and polysaccharides. Disaccharides are also simple sugars. Disaccharides are classified into two groups according to their reducing strength: Reducing and Non-reducing sugars. When a polymer is formed from a monomer, a condensation reaction occurs that forms a glycosidic bond and water molecule is lost. Starch, glycogen and cellulose are examples of polysaccharides. Starch is found in many parts of plant cell and consists of amylose and amylopectin. Glycogen is the major carbohydrate storage product found in humans. It is present in liver, muscles and brain.

Cellulose is the most abundant organic molecule on Earth. It makes up around 50% of all organic carbon.

Question: 1

Name the linkage which connects monosaccharide units in polysaccharides.

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Remember: A glycosidic bond forms between the anomeric carbon of one sugar and a hydroxyl group of another sugar.
Updated On: Jul 8, 2025
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Solution and Explanation

Step 1: Polysaccharides are polymers made up of repeating monosaccharide units.
Step 2: These monosaccharides are joined together by a covalent bond known as the glycosidic bond.
Step 3: This bond is formed during a condensation reaction, where a water molecule is eliminated.
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Question: 2

Carbohydrates are classified on the basis of their behaviour on hydrolysis. Write the hydrolysis products of sucrose.

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Hydrolysis of disaccharides always gives the constituent monosaccharides. Use the enzyme-specific method (e.g., invertase for sucrose) in biology contexts.
Updated On: Jul 8, 2025
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Solution and Explanation

Step 1: Sucrose is a disaccharide composed of one glucose unit and one fructose unit.
Step 2: Upon hydrolysis (in the presence of dilute acid or the enzyme invertase), sucrose breaks down into: \[ \text{Sucrose} + \text{H}_2\text{O} \longrightarrow \text{Glucose} + \text{Fructose} \] Step 3: Both glucose and fructose are monosaccharides.
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Question: 3

Write two differences between Amylose and Amylopectin.

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Amylose: Linear and forms helical structures.
Amylopectin: Branched and more abundant in starch.
Updated On: Jul 8, 2025
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Solution and Explanation

Amylose: - Consists of long unbranched chains of $\alpha$-D-glucose units.
- Contains only $\alpha$(1$\rightarrow$4) glycosidic bonds.
Amylopectin: - Is a highly branched molecule.
- Contains both $\alpha$(1$\rightarrow$4) and $\alpha$(1$\rightarrow$6) glycosidic linkages at branch points.
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