HUSNA SHARIFHUSNA SHARIF

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Carrot cell wallCarrot cell wall

THE CELL WALL

plant cells separated by transparent cell walls

• Introduction to cell wallIntroduction to cell wall• Morphology of cell wallMorphology of cell wall• Composition of cell wallComposition of cell wall• Prokaryotic cell wallProkaryotic cell wall• Eukaryotic cell wallEukaryotic cell wall• Functions of cell wallFunctions of cell wall

INTRODUCTIONINTRODUCTION• FOUND IN PLANT CELLS AND ABSENT IN FOUND IN PLANT CELLS AND ABSENT IN

ANIMALSANIMALS• ALSO FOUND IN BACTERIAL,ALGAL, AND ALSO FOUND IN BACTERIAL,ALGAL, AND

FUNGAL CELLSFUNGAL CELLS• OUTER MOST LAYEROUTER MOST LAYER• FAIRLY RIGIDFAIRLY RIGID• OUTER TO THE CELL MEMBRANEOUTER TO THE CELL MEMBRANE• NON LIVING SUBSTANCENON LIVING SUBSTANCE• MAIN DIFFERENCE BETWEEN PLANT AND MAIN DIFFERENCE BETWEEN PLANT AND

ANIMAL CELLSANIMAL CELLS

plant cells separated by transparent cell walls

STRUCTURESTRUCTURE• THREE MAIN THREE MAIN

LAYERSLAYERS1.1. MIDDLE LAMELLAMIDDLE LAMELLA2.2. PRIMARY WALLPRIMARY WALL3.3. SECONDARY SECONDARY

WALLWALL

Layers of cell wall

MIDDLE LAMELLAMIDDLE LAMELLA• COMPOSED OF PECTIC ACIDCOMPOSED OF PECTIC ACID• IST FORMED LAYERIST FORMED LAYER• BETWEEN PRIMARY WALLS OF BETWEEN PRIMARY WALLS OF

ADJACENT CELLSADJACENT CELLS• DOES NOT CONTAIN CELLULOSEDOES NOT CONTAIN CELLULOSE• HELP IN TISSUE FORMATIONHELP IN TISSUE FORMATION• ALSO CALLED CEMENTED SUBSTANCEALSO CALLED CEMENTED SUBSTANCE

PRIMARY WALLPRIMARY WALL• COMPOSED OF CELLULOSE ,PECTIC COMPOSED OF CELLULOSE ,PECTIC

ACID AND LEGNINACID AND LEGNIN• CELLULOSE ARRANGED INA CRISS CELLULOSE ARRANGED INA CRISS

CROSS NMANNERCROSS NMANNER• TRUE WALLTRUE WALL

SECONDARY WALLSECONDARY WALL• INNER MOST LAYER OF CELL WALLINNER MOST LAYER OF CELL WALL• EXTREMELY THICKEXTREMELY THICK• CELL DIES WHEN CELL WALL FORMS CELL DIES WHEN CELL WALL FORMS

COMPLETELYCOMPLETELY• MADE UP OF MADE UP OF

CELLULOSE,LEGNIN,SILICA,AND CELLULOSE,LEGNIN,SILICA,AND WAXES ETCWAXES ETC

COMPOSITION OF CELL COMPOSITION OF CELL WALLWALL• DIFFERENT IN DIFFERENT SPECIESDIFFERENT IN DIFFERENT SPECIES• IN PLANT FROM CELLULOSEIN PLANT FROM CELLULOSE• IN BACTERIA PEPTIDOGLYCANIN BACTERIA PEPTIDOGLYCAN• IN FUNGI CHITININ FUNGI CHITIN• IN ALGAE GLYCOPROTIENS AND IN ALGAE GLYCOPROTIENS AND

POLYSACCARIDESPOLYSACCARIDES

PROKARYOTIC CELL WALLPROKARYOTIC CELL WALL(BACTERIAL CELL WALL)(BACTERIAL CELL WALL)• PRESENT IN MOST OF BACTERIAPRESENT IN MOST OF BACTERIA• ABSENT IN SOME e.g. MYCOPLASMAABSENT IN SOME e.g. MYCOPLASMA• MADE UP OF MUREINMADE UP OF MUREIN• HAS NO CELLULOSEHAS NO CELLULOSE• MUREIN ALSO CALLED AS MUREIN ALSO CALLED AS

PEPTIDOGLYCANPEPTIDOGLYCAN• PEPTIDO FOR AMINO ACIDS AND GLYCAN PEPTIDO FOR AMINO ACIDS AND GLYCAN

FOR SUGARS(DISACCARIDS)FOR SUGARS(DISACCARIDS)

Gram positive bacterial cell wall

Gram negative bacterial cell wall

EUKARYOTIC CELL WALLEUKARYOTIC CELL WALL

• ALGAL CELL WALLALGAL CELL WALL

• FUNGAL CELL WALLFUNGAL CELL WALL

ALGAL CELL WALLALGAL CELL WALL• HAVE CELLULOSE AND A VERIETY OF HAVE CELLULOSE AND A VERIETY OF

GLYCOPROTIENSGLYCOPROTIENS• ALGENIC ACID,SULFONATED ALGENIC ACID,SULFONATED

POLYSCCARIDES,SPOROPOLLENIN, POLYSCCARIDES,SPOROPOLLENIN, AGAROSE, PORPHYRAN ARE DIFFERENT AGAROSE, PORPHYRAN ARE DIFFERENT COMPOUNDS USED IN CELL WALLS OF COMPOUNDS USED IN CELL WALLS OF VARIOUS ALGAL SPECIESVARIOUS ALGAL SPECIES

• DIATOMS(specie of algae) SYNTHESIZE DIATOMS(specie of algae) SYNTHESIZE THEIR CELL WALL FROM SILICIC ACIDTHEIR CELL WALL FROM SILICIC ACID

CELL WALLS OF DIATOMS

FUNGAL CELL WALLFUNGAL CELL WALL• NOT ALL SPECIES OF FUNGI HAVE NOT ALL SPECIES OF FUNGI HAVE

CELL WALLSCELL WALLS• MOSTLY FUNGAL CELL WALLS ARE MOSTLY FUNGAL CELL WALLS ARE

MADE OF UP CHITINMADE OF UP CHITIN• SOME CONTAIN OTHER SOME CONTAIN OTHER

POLYSACCHARIDES ALSOPOLYSACCHARIDES ALSO• CELLULOSE IS ABSENT CELLULOSE IS ABSENT

Chemical structure of a unit from a chitin polymer chain.

FUNCTIONS OF CELL WALLFUNCTIONS OF CELL WALL• SHAPESHAPE• PROTECTIONPROTECTION• TRANSPORTTRANSPORT• SRENGTH AND REGIDITYSRENGTH AND REGIDITY• PERMEABILITYPERMEABILITY• REGULATION OF CELL VOLUMEREGULATION OF CELL VOLUME

• CREATES STABLE OSMOTIC CREATES STABLE OSMOTIC PRESSUREPRESSURE

• HYDROPHILIC HYDROPHILIC • CONTROL RATE AND DIRECTION OF CONTROL RATE AND DIRECTION OF

GROWTHGROWTH• CARBOHYDRATE STORAGECARBOHYDRATE STORAGE• ECONOMIC PRODUCTSECONOMIC PRODUCTS