Starch vs Cellulose: what's the difference?
A-Level Biology
Both are polysaccharides of glucose, but the glucose type and bonding make one a store and the other structural.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Starch vs Cellulose — side by side
| Starch | Cellulose | |
|---|---|---|
| Monomer | α-glucose | β-glucose |
| Chain shape | Coiled/branched (amylose + amylopectin) | Straight, unbranched |
| Function | Energy store in plants | Cell-wall structure/strength |
| Arrangement | Compact for storage | Parallel chains held by hydrogen bonds → microfibrils |
Exam tip — how to tell them apart: α-glucose → starch (store). β-glucose → cellulose (structural). Alternate β-glucose units are flipped 180°, giving straight chains.
Common trap: Both are glucose polymers — the mark is for linking the α/β glucose and the bonding to the function.
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