Q.1 The glycosidic linkages in cellulose and amylose are ________, respectively.
(A) α 1-4 and β 1-4
(B) β 1-4 and α 1-4
(C) β 1-4 and α 1-6
(D) α 1-4 and α 1-2

The glycosidic linkages in cellulose and amylose are β 1-4 and α 1-4, respectively, making option (B) correct.

Option Analysis

Cellulose features β 1-4 glycosidic bonds between glucose units, forming straight, rigid chains ideal for plant cell wall structure. Amylose, a starch component, uses α 1-4 linkages, creating a helical structure digestible by human enzymes like amylase.

• (A) α 1-4 and β 1-4: Reverses the linkages; α 1-4 suits amylose, not cellulose’s β form.

• (B) β 1-4 and α 1-4: Matches cellulose (β for rigidity) and amylose (α for helices).

• (C) β 1-4 and α 1-6: Cellulose correct, but α 1-6 occurs in amylopectin’s branches, not linear amylose.

• (D) α 1-4 and α 1-2: α 1-4 fits amylose but not cellulose; α 1-2 rare, seen in some disaccharides.

Introduction to Glycosidic Linkages

Glycosidic linkages in cellulose and amylose define their structures and functions in biology. Cellulose uses β 1-4 bonds for plant strength, while amylose employs α 1-4 for energy storage. These differences are crucial for CSIR NET exams in carbohydrates and polysaccharides.

Cellulose Structure

Cellulose consists of linear β-D-glucose chains linked by β 1-4 glycosidic bonds, enabling hydrogen bonding into microfibrils. This configuration resists digestion, unlike α-linked polysaccharides.

Amylose Structure

Amylose forms helical chains of α-D-glucose via α 1-4 glycosidic linkages, a component of starch for rapid hydrolysis. Branching absent here distinguishes it from amylopectin.