What is role of cell wall in plant cells?

Answer 1

To keep the contents of the cell within it, and provide rigidity, form and protection to the cell.

Typically composed of cellulose and other organic materials that may contain extracellular enzymes and other substances.

Answer 2

Plant cell walls have a number of functions: they provide rigidity to the cell for structural and mechanical support, maintaining cell shape, the direction of cell growth and ultimately the architecture of the plant. The cell wall also prevents expansion when water enters the cell. The term turgor is used to describe this pressure that is induced by excess water inside the plant cell. Cell walls protect against pathogens and the environment and are a store of carbohydrates for the plant. The cell wall is constructed primarily from a carbohydrate polymer called cellulose.

The middle lamella is laid first, formed from the cell plate during cytokinesis, and the primary cell wall is then expanded inside the middle lamella. The actual structure of the cell wall is not clearly defined and several models exist - The covalently linked cross model, the tether model, the diffuse layer model and the stratified layer model are to name a few. However, the primary cell wall, can be defined as composed of cellulose microfibrils aligned at all angles. Microfibrils are held together by hydrogen bonds to provide a high tensile strength. The cells are held together and share the gelatinous membrane called the middle lamella, which contains magnesium and calcium pectates (salts of pectic acid). Cells interact though plasmodesma(ta), which are inter-connecting channels of cytoplasm that connect to the protoplasts of adjacent cells across the cell wall.

In some plants and cell types, after a maximum size or point in development has been reached, a secondary wall is constructed between the plant cell and primary wall. Unlike the primary wall, the microfibrils are aligned mostly in the same direction, and with each additional layer the orientation changes slightly. Cells with secondary cell walls are rigid. Cell to cell communication is possible through pits in the secondary cell wall that allow plasmodesma to connect cells through the secondary cell walls.

Composition of plant cell walls
The major carbohydrates making up the primary 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.

Plant cells walls also incorporate a number of proteins; the most abundant include hydroxyproline-rich glycoproteins (HRGP), also called the extensins, the arabinogalactan proteins (AGP), the glycine-rich proteins (GRPs), and the proline-rich proteins (PRPs). With the exception of glycine-rich proteins, all the previously mentioned proteins are glycosylated and contain hydroxyproline (Hyp). Each class of glycoprotein is defined by a characteristic, highly repetitive protein sequence. Chimeric proteins contain two or more different domains, each with a sequence from a different class of glycoprotein. Most cell wall proteins are cross-linked to the cell wall and may have structural functions.

Secondary cell walls may contain lignin and suberin, making the walls rigid.

The relative composition of carbohydrates, secondary compounds and protein varies between plants and between the cell type and age.

Answer 3

To keep the contents of the cell within it, and provide rigidity, form and protection to the cell.

Typically composed of cellulose and other organic materials that may contain extracellular enzymes and other substances.

Answer 4

1 for shape 2 - for seprate between celles 3- for contact 4- for all celles be independent for osmos hyper and hypo and...