CELLWALL

The membrane which is out side the Plasma membrane is called Cellwall.

Discovered by - Robert Hook

- it has outer wall of cell. 

- rigid membrane. 

- provide Strangth of cell. 

- it is found in Plant cell, Fungi, Prokaryot(except Mycoplasma). 

NOTE-Mycoplasma is smallest cell without cellwall. 

Chemical nature of cell wall-:

1) Prokaryotic cell wall - Peptidoglycon. 

2) Fungus cell wall-Chitin (homo polysaccharides which is N-acetyl glucosamine). 

3) Plant cell wall-Cellulose.

NOTE-In animal cellwall are absent. 

Structure of cell wall-:

Cell wall is Madeup of 3 layer-:

           Middle lamella (innermost layer) 

             # Madeup of Ca & Mg pactet

                       ।।। 

          1) Primary cellwall

            # Madeup of Hemicellulose 

            # meristemic cell found only this layer. 

                       ।।। 

         2) Secondary cellwall

           # Madeup of cellulose. 

           # it arranged in 3 layer S1,S2,S3 in different orientation. 

                       ।।।

          3) Tertiary cellwall (outermost layer) 

           # it is Madeup of Lignin & Xylene. 

           # it is not uniform layer. 

           # it help in for extra mechanical support.

      STRUCTURE OF CELLWALL

Pit/Pore-: at which point Secondary wall is absent is called Pit. 

Pits are two type-:

1)Simple Pit - Found in Angiosperm. 

2)Borderd Pit-Found in Gymnosperm.

Function of Cellwall-:

# Provide shape, rigidity of cell. 

# Primary cellwall help in enzymatic reaction.

# help in apoplast transfer of water Absorption. 

# Cutin is deposited into secondary wall which help to prevent loss of water.

# Lignine provide machenical support.

NOTE- if Lignine deposition is uniformly then cell are die. 

                    e.g. Schelranchyama

                ✴✴THANK YOU✴✴