Introduction-to-Macromolecular-Components-of-the-Cell-Wall.pptx

Macromolecular components of the cell wall: Cell wall layers; origin
and growth of cell wall; Plasmodesmata.

1. Introduction to Macromolecular Components of the Cell Wall The cell wall is a rigid structure that surrounds the plasma membrane of plant cells and bacteria. It provides structural support and protection. The cell wall is composed of various macromolecules, primarily cellulose, hemicellulose, and pectin. by unknown name

2. Cell Wall Layers Primary Cell Wall The primary cell wall is the first cell wall to be laid down in a newly formed plant cell. It is relatively thin and flexible, allowing for cell expansion. Secondary Cell Wall The secondary cell wall is deposited inside the primary cell wall in some plant cells. It is thicker and more rigid than the primary wall and provides additional support. Tertiary Cell Wall The tertiary cell wall is the innermost layer of the cell wall. It is often found in specialized cells such as xylem and phloem.

3. Primary Cell Wall 1 Cellulose Microfibrils Cellulose microfibrils are long, thin strands of cellulose molecules that provide structural support. 2 Hemicelluloses Hemicelluloses are branched polysaccharides that bind to cellulose microfibrils and help to cross-link them. 3 Pectins Pectins are complex polysaccharides that form a gel-like matrix within the primary cell wall. 4 Proteins Proteins are also present in the primary cell wall and play a variety of roles, such as enzymes and structural components.

4. Secondary Cell Wall Lignin Lignin is a complex polymer that is deposited in the secondary cell wall of woody plants. Suberin Suberin is a waxy substance that is deposited in the secondary cell wall of some plant cells. Cutin Cutin is a waxy substance that is deposited in the cell wall of epidermal cells.

5. Tertiary Cell Wall The tertiary cell wall is formed in some specialized cells. It is often associated with a thickened secondary cell wall and can be impregnated with lignin, suberin, or other substances. Its composition and function vary depending on the cell type.

6. Origin and Growth of the Cell Wall 1 Cell Division The cell wall originates during cell division when a new cell plate forms between the daughter cells. 2 Cellulose Synthesis Cellulose microfibrils are synthesized by enzymes called cellulose synthases located in the plasma membrane. 3 Cell Wall Expansion The cell wall expands as the cell grows and takes on its characteristic shape.

7. Deposition of Cell Wall Components Golgi Apparatus Pectins and hemicelluloses are synthesized in the Golgi apparatus. Vesicle Transport These molecules are then packaged into vesicles and transported to the cell wall. Cell Wall Incorporation The vesicles fuse with the plasma membrane and release their contents into the cell wall.

8. Cell Wall Expansion and Thickening Expansion Driven by turgor pressure and the deposition of new cell wall material. Thickening Occurs by the deposition of additional layers of cell wall material, often in the secondary cell wall.

9. Structure and Function of Plasmodesmata Intercellular Connections Plasmodesmata are microscopic channels that connect adjacent plant cells. They are lined by the plasma membrane and allow for the passage of small molecules and macromolecules between cells. Intercellular Communication Plasmodesmata facilitate communication between cells, enabling the transport of signals, nutrients, and other essential molecules. Transport of Macromolecules Plasmodesmata can also transport larger molecules, including proteins, RNA, and viruses, between cells.

10. Conclusion: Importance of Cell Wall Macromolecules The macromolecular components of the cell wall play essential roles in plant growth, development, and defense. These components provide structural support, regulate cell expansion, facilitate communication between cells, and protect against pathogens and herbivores.