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Difference between Primary Cell Wall and Secondary Cell Wall

Cell wall was first discovered by Robert Hooke in 1665.  In cells of bacteria, cyanobacteria, protists, fungi and plants, a thick, rigid, protective cell wall is present outside the plasma membrane. One of the most important differences between plant and animal cells is the presence of cell wall in plant cells.
Primary and Secondary Cell wall

Composition of cell wall: The composition of cell wall varies in different groups.
  • Bacteria: Peptidoglycan cell wall: Cell wall is composed of protein-lipid-polysaccharides having two important chemical components: N -acetyl glucosamine (NAG) and N-acetyl muramic acid (NAM). Read more
  • Algae: Cell wall contains cellulose and a variety of glycoproteins. Read more
  • Fungi: Cell wall is made up of chitin (Polymer of N-acetyl glucosamine)
  • Plants: Cell wall is made up of cellulose (β-D-glucose units), hemicellulose (Arabinose, mannose, xylose, galactose, etc.) and pectin (Galactose, galacturonic acid and arabinose).
  • A typical cell is made up of four layers: middle lamella, primary, secondary and tertiary wall. Middle lamella is the cementing layer between the cells. It is made up of Ca and Mg pectates. Read more

Primary Cell Wall and Secondary Cell Wall
No
Features
Primary cell wall
Secondary cell wall
1
Occurrence
In all the plant cells

In only mature and non dividing cells
2
Position
Inner to middle lamella

Inner to primary cell wall

3
Nature
Elastic and thinner (1-3m)

Inelastic, rigid and thicker
 (5-10m)

4

Nature of growth
Intussusceptional
Accretional
5

Pits
Absent
Present
6

Additional materials
Absent
Present:
lignin, suberin or cutin
7

Amount of cellulose
Low
High
8
Extensibility
Present
Generally absent
9

Arrangement of fibrils
Wavy and loosely arrangement
Closely, straight and parallel arranged
10
Hydration
More (60%)
Less (30-40%

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