Q61. Name the structures given below in the order of their appearance and identify corresponding glycosidic linkages
Step-by-Step Identification of Structures
🟠 First Structure (Left Side)
- Shows branching of glucose chains
- Side chains arise from C6 carbon
- Backbone is helical
Linkages present:
- α(1→4) backbone
- α(1→6) branching points
Identified as: Amylopectin
Reason: Highly branched storage polysaccharide found in starch.
🔵 Second Structure (Right Side)
- Long straight chain
- No branching
- Alternating glucose orientation
- Rigid fiber-like structure
Linkage present: β(1→4)
Identified as: Cellulose
Reason: Linear β bonds form strong hydrogen-bonded fibers in plant cell walls.
📊 Correct Order of Structures
| Position | Structure | Glycosidic Linkage |
|---|---|---|
| First | Amylopectin | α(1→4) + α(1→6) |
| Second | Cellulose | β(1→4) |
Option-wise Explanation
Option A
❌ Incorrect – Cellulose has β(1→4), not β(1→6).
Option B
❌ Incorrect – β(2→4) linkage does not exist here and dextran is not shown.
Option C
❌ Incorrect – Cellulose contains β bonds, not α bonds.
Option D
❌ Incorrect – Second structure is β-linked cellulose, not amylose.
Quick Comparison Table
| Feature | Amylopectin | Cellulose |
|---|---|---|
| Type | Storage polysaccharide | Structural polysaccharide |
| Bond type | α(1→4), α(1→6) | β(1→4) |
| Shape | Branched | Straight chain |
| Digestibility | Digestible | Indigestible to humans |
Final Answer
First → Amylopectin (α1→6 branching)
Second → Cellulose (β1→4)
