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1ST Chapter
Cell and it’s structure
What can you see?
A well protected home with surrounding wall
Do you know Like this plants cell have a outer protective wall?
So….. What is the name of this wall for a plant cell?
Toady's Part Content
Cell wall
Learning outcomes
After end of this lesson students will be able
to…
 explain the structure of the cell wall;
 mention the importance of the cell wall in
plants life.
Posible question
Knowledge based
1. What is called cell wall?
2. What is called pit, pitmembrane?
Understanding question
1.What is meaning by plasmadesmata?
Application:
1.Describe the physical structure of cell wall.
2. Describe the ultra structure of cell wall.
Higher order:
Analyzing the importance of the cell wall in life
Animal cell
Plant cell
Cell wall
Plasma
membrane
Definition
 The cellulose made, hard and nonliving membrane around the
protoplasm of each cell is said to be cell wall.
A matured cell wall is divided into three layers:
Middle lamella
Primary cell wall
Secondary cell wall
Middle lamella
Primary cell wall
Secondary cell wall
 Middle lamella
Middle
lamella
Pit field
Pit
Pit membrane
Other components of the cell wall:
Pit field : It is the thinnest part of the wall. Primary and
secondary walls are absent here.
Pit membrane: . In the pit field area middle lamella is called the
pit membrane.
Pit pair: Two pits lying face to face are known as pit pair.
Plasmodesmata
The cell wall is interrupted at intervals by narrow pores
carrying fine stands of cytoplasm which join the living
cell s to each another. These are called plasmodesmata.
 On the middle lamella ,
by the deposition of
cellulose, hemicellulose
and glycoprotein a thin
layer is called primary
cell wall. This layer is
thicker 1-3 ´m
 In some cell (ex. trachied.
Fibres etc) different chemicals, like
suberin, lignin deposit on the primary
layer is called secondary wall.
 This layer is thicker 5-10 µm
 Generally it occurs after
full maturation of the cell.
 Secondary wall is not formed in
meristems
 It has three layer
Secondary cell
wall
Intra layer
Middle layer
Extra layer
Chemical structure:
Cellulose
Hemi-cellulose
Lignin
Ultra structure of cell wall
1-3 thousands cellulose = cellulose chain.
1oo cellulose chain = 1 crystalline micelles
20 micelle = 1microfibryl
250 microfibryl = 1 macrofybryl
The smallest unit of cell wall is micelles
cellulose
100
micelle
20
Microfibril
250
Macrofibril
Cell wall
Function
1.Give definite shape of the cell
2.Give protection of outside attack of the cell
3. It provides the cell with essential energy and strength
4.Helps in absorption of water and minerals in plant.
5.Separate the cells from each other
Team work
Possible knowledge based & understanding question listed.
Group-a: describe the physical structure of cell wall.
Group-b: describe the ultra structure of cell wall.
Evaluation
1. Which is the unique characteristics of a plant cell?
2. How many parts divided a completely developed plant cell wall?
3. Which element causes for jelly like substance of the middle
lamella?
4. Which cell have no middle lamella?
5. Which element deposited to formed primary cell wall and what
types of compounds of this elements?
6. What is the thickness of secondary cell wall?
7. Which cell have no secondary cell wall?
8. How many layer formed in secondary cell wall?
9. What is called the cytoplasmic conjoint microscopic fibrils which
found in cell wall pores?
10.What is the main composed element of cell wall?
11.Which is the smallest unit in the cell wall?
Limo thought under a large tree that the outer layer oh that
tree is so hard and protected the tree from outside attack ,
but he has no like this part in his body. He thought this hard
like part of tree may be help in many purposes.
a. What is cell wall?
b. What do you mean by plasmodesmata?
c. Described the stem mentioned parts physical structure.
d. Analysis the last word of stem mentioned.
Thank you