Cellulose is an organic compound categorised as a polysaccharide, consisting of glucose subunits. Predominantly found in bacterial and plant cells, it plays a crucial role in their cell walls, contributing to the structural integrity of plants. This article explores the structure, properties, synthesis, occurrence, and significance of cellulose in plants, as well as its industrial applications.



Cellulose is composed of thousands of D-glucose subunits linked by beta 1-4 glycosidic bonds. Unlike other polysaccharides, cellulose features a reversed orientation of glucose molecules, with a beta orientation. Alternate inversion of glucose molecules is necessary to form beta 1-4 glycosidic bonds. Cellulose exists as an unbranched, linear molecule, with its chains arranged parallel to each other, forming strong cellulose microfibrils through hydrogen bonds.



Cellulose stands out from other polysaccharides due to its unique structure, leading to specific properties:

1. Abundance: Most abundant carbohydrate in nature.
2. Insolubility: Does not dissolve in water.
3. Crystalline Solid: Exhibits a white powdery appearance.
4. High Tensile Strength: Hydrogen bonds between cellulose microfibrils provide strength comparable to steel.
5. Solubility in Organic Solvents: Can dissolve in certain organic solvents.


Cellulose synthesis occurs in plants and bacteria. In plants, special complexes called rosette terminal complexes, containing cellulose synthase enzymes, facilitate the polymerisation of glucose residues to form cellulose chains and the assembly of cellulose microfibrils. Bacteria use similar enzymes for cellulose synthesis, possibly acquired by plants through endosymbiosis. Animals, such as tunicates, also synthesise cellulose in a process similar to plants and bacteria.


Cellulose is omnipresent in plant cell walls, bacteria, and algae. Pure cellulose is notably found in cotton (about 98% cellulose) and wood. Some animals, like tunicates, contain cellulose in their shells.


Cellulose degradation, termed cellulolysis, occurs in plants during diseases when pathogens release cellulolytic enzymes. In animals, cellulose is digested in the digestive tract of herbivores with the help of symbiotic bacteria producing cellulase enzymes. Thermolysis refers to cellulose breakdown at high temperatures.


Cellulose serves critical roles in various domains:

1. **Plants:** Provides rigidity to plant cells, maintaining their shape.
2. **Microorganisms:** Contributes to cell wall structure in bacteria and algae.
3. **Animals:** Acts as a dietary carbohydrate source for herbivores.
4. **Industry:** Utilised in paper, textile, electrical insulation, biofuel, gunpowder, drug stabilisation, and chromatography.


Cellulose, a key structural polysaccharide in plants, exhibits a unique glucose-linked structure, providing strength and rigidity. Its synthesis involves specific enzyme complexes in plants and bacteria. The cellulose microfibrils in plant cell walls are reinforced by a polysaccharide matrix. Cellulose's abundance and diverse applications underscore its significance in nature and industry.


Test Yourself 

1. What category does cellulose belong to?
- a) Proteins
- b) Polysaccharides
- c) Lipids
- d) Nucleic Acids

2. What is the basic unit of cellulose?
- a) Amino acids
- b) Fatty acids
- c) Glucose
- d) Nucleotides

3. Where is cellulose primarily found?
- a) Animal cells
- b) Fungi
- c) Bacterial and plant cells
- d) Viruses

4. What role does cellulose play in plants?
- a) Energy storage
- b) Structural support
- c) Enzyme production
- d) Photosynthesis

5. How are glucose subunits in cellulose linked?
- a) Alpha 1-4 glycosidic bonds
- b) Beta 1-4 glycosidic bonds
- c) Peptide bonds
- d) Ester bonds

6. What is the orientation of glucose molecules in cellulose?
- a) Alpha orientation
- b) Beta orientation
- c) Gamma orientation
- d) Delta orientation

7. Why are every alternate glucose molecules inverted in cellulose?
- a) To increase solubility
- b) To form alpha bonds
- c) To make beta 1-4 glycosidic bonds
- d) To prevent synthesis

8. How are the polymeric chains of glucose arranged in cellulose?
- a) Coiling
- b) Helix formation
- c) Linear pattern
- d) Branched structure

9. What type of bonds firmly hold the cellulose chains together?
- a) Ionic bonds
- b) Covalent bonds
- c) Hydrogen bonds
- d) Van der Waals forces

10. What structures do cellulose chains form in plant cells?
- a) Microtubules
- b) Microfilaments
- c) Microfibrils
- d) Microsomes

11. In which organisms is cellulose synthesis limited to?
- a) Animals
- b) Plants and bacteria
- c) Fungi
- d) Viruses

12. What are the complexes responsible for cellulose synthesis in plants?
- a) Endoplasmic reticulum
- b) Golgi apparatus
- c) Rosette terminal complexes
- d) Lysosomes

13. What function do rosette terminal complexes perform?
- a) Energy production
- b) DNA replication
- c) Polymerization of glucose residues and assembly of cellulose microfibrils
- d) Protein synthesis

14. What serves as a primer in the synthesis of cellulose chains in plants?
- a) ATP
- b) ADP
- c) Sitosterol-beta-glucoside
- d) Glucagon

15. Where does the cellulase enzyme cleave the cellulose chain in plants?
- a) In the cytoplasm
- b) In the nucleus
- c) In the cell wall
- d) In the vacuole

16. What is the primary component of the polysaccharide matrix in the plant cell wall?
- a) Starch
- b) Cellulose
- c) Glucans and arabinoxylans
- d) Hemicellulose

17. What strengthens the network formed by the polysaccharide matrix in the plant cell wall?
- a) Oxygen
- b) Calcium
- c) Nitrogen
- d) Phosphorus

18. What is the most abundant biopolymer on Earth?
- a) DNA
- b) Protein
- c) Cellulose
- d) RNA

19. Where is cellulose found in animals?
- a) In the bloodstream
- b) In bones
- c) In the nervous system
- d) In the shells of tunicates

20. What is the process of cellulose degradation called?
- a) Glycolysis
- b) Glycogenesis
- c) Cellulolysis
- d) Lipolysis



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