Sunday, December 20, 2009




To study about cellwall constituents and cell inclusions


A membrane of the cell that forms external to the cell membrane whose main role is to give cells rigidity, strength and protection against mechanical stress. It is found in cells of plants, bacteria, archaea, fungi, and algae. Animals and most protists do not have cell walls.
The cell wall is composed of cellulose fiber, polysaccharides, and proteins. In new cells the cell wall is thin and not very rigid. This allows the young cell to grow. This first cell wall of these growing cells is called the primary cell wall. When the cell is fully grown, it may retain its primary wall, sometimes thickening it, or it may deposit new layers of a different material, called the secondary cell wall.
cell's cell wall interacts with its neighbors to form a tightly bound plant structure. Despite the rigidity of the cell wall, chemical signals and cellular excretions are allowed to pass between cells.
cell wall consisting of many layers of peptidoglycan and teichoic acids. Gram-negative bacteria have relatively thin cell wall consisting of few layers of peptidoglycan.
Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins.
The major carbohydrates making up the primary (growing) plant cell wall are cellulose, hemicellulose and pectin.The cellulose microfibrils are linked via hemicellulosic tethers to form the cellulose-hemicellulose network, which is embedded in the pectin matrix.
Like plants, algae have cell walls. Algal cell walls contain cellulose and a variety of glycoproteins. The inclusion of additional polysaccharides in algal cells walls is used as a feature for algal taxonomy.
Most true fungi have a cell wall consisting largely of chitin and other polysaccharides. True fungi do not have cellulose in their cell walls, but some fungus-like organisms do.

Cells can be isolated from tissues for ex vivo culture in several ways.
Cells can be easily purified from blood, however only the white cells are capable of growth in culture.
Mononuclear cells can be released from soft tissues by enzymatic digestion with enzymes such as collagenase, trypsin, or pronase, which break down the extracellular matrix.
place the slide containing the extracted cell under compound microscope
observe it under compound microscope clearly.

Three strata or layers may be found in plant cell walls:
* The middle lamella, a layer rich in pectins. This outermost layer forming the interface between adjacent plant cells and glues them together.
* The primary cell wall, generally a thin, flexible and extensible layer formed while the cell is growing.
* The secondary cell wall, a thick layer formed inside the primary cell wall after the cell is fully grown. It is not found in all cell types. In some cells, such as found xylem, the secondary wall contains lignin, which strengthens and waterpoofs the wall.


Components of the cell wall are clearly observed by a compound microscope

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