Plant Cell Wall TOPIC FOR Class 11
Plant Cell Wall:
In plant cells, the cell wall is a prominent feature and serves several important functions:
Structural Support: The primary function of the plant cell wall is to provide structural support to the plant cell. It helps maintain the cell's shape and prevents it from collapsing.
Protection: The cell wall acts as a protective barrier, shielding the plant cell from external mechanical damage and pathogens.
Cellular Communication: Plasmodesmata, microscopic channels in the cell wall, allow for communication and transport of materials between adjacent plant cells.
Regulation of Water Uptake: The cell wall plays a role in regulating water uptake and maintaining cell turgor pressure. Turgor pressure is essential for cell rigidity.
Composition of Plant Cell Wall:
Cellulose: The main component of plant cell walls is cellulose, a complex carbohydrate made up of glucose units. Cellulose forms long chains that are bundled together to create a strong and rigid structure.
Hemicellulose: Another polysaccharide found in the plant cell wall, contributing to its overall strength.
Pectin: A gel-like substance that fills the spaces between cellulose fibers, providing flexibility and contributing to cell adhesion.
Proteins: Various proteins are embedded in the cell wall, contributing to its overall structure and function.
Fungal Cell Wall:
In fungi, the cell wall serves similar functions but is composed of different materials:
Chitin: Fungal cell walls contain chitin, a complex polysaccharide made of N-acetylglucosamine. Chitin provides strength and rigidity to the fungal cell wall.
Glucans: Other polysaccharides, such as glucans, may also be present in fungal cell walls.
Bacterial Cell Wall:
Bacterial cell walls are diverse and can be classified into two main types:
Gram-Positive Cell Wall:
- Contains a thick layer of peptidoglycan, a polymer of sugars and amino acids.
- May also contain teichoic acids.
Gram-Negative Cell Wall:
- Has a thin layer of peptidoglycan surrounded by an outer membrane.
- The outer membrane contains lipopolysaccharides.
Archaeal Cell Wall:
Archaeal cell walls can vary widely among different archaea. Some archaea have cell walls made of pseudopeptidoglycan, glycoproteins, or other unique structures.