Cell Wall: Structure and Function complete notes simple and easy.

 What is Cell wall?

Some organisms like plants and fungi have an outer layer around cells called as Cell Wall. The composition of cell wall varies in plants and fungi.

• All plants have cell wall except some.
• Cell wall provides protection to the protoplasm.
• The cell wall surrounds the plasma membrane of plant cells and provides tensile strength and protection against mechanical and osmotic stress.
• Cell wall of fungi is made up of Chitin a Polysaccharide.
• In Plants, structurally it is mainly composed of Cellulose, Hemicellulose and Pectic substance.
• These three substances are Polysaccharides in nature.
• The main constituent of cell wall is cellulose.

PLANT CELL WALL

• The main constituent of cell wall is Cellulose.
• Cellulose is a polymer of beta-D-Glucose, each monomer joined together by beta 1-4 linkage of glycosidic bond.
• Once the polysaccharide Cellulose lie adjacent to each other they start forming microfibrils.
• Adjacent cellulose packed together parallelly to form cellulose microfibrils.
• The polymer of cellulose grows at one end with help of complex of enzymes that add new glucose residue once at a time.
• These enzymes are intrinsic membrane proteins named as cellulose synthase
• Cellulose in microfibrils are not able to link together so they link together with help of Matrix material.
• Matrix material are produced in dictyosome and brought to cell wall via vesicles that fuses with Plasma Membrane.
• Matrix material includes Hemicellulose and Pectic polysaccharides.
• Microfibrills has great strength but it get increased by matrix.
• Cellulose microfibrils link together with each other with help of another polysaccharide HemiCellulose, it forms hydrogen bonding with cellulose called as HemiCellulose.
• In multicellular plants wall of one cell is attached to adjacent cell by an ADHESION layer composed of Pectic substance (Galactouronans) called as MIDDLE LAMELLA.

STRUCTURE

Watch complete video with explanation: