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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