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.

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

Difference between:

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%