Cell wall chemical components

Fibers for commercial and domestic use are broadly classified as natural or synthetic. The natural fibers are vegetable, animal, or mineral ia origin. Vegetable fibers, as the name implies, are derived from plants. The principal chemical component ia plants is cellulose, and therefore they are also referred to as ceUulosic fibers. The fibers are usually bound by a natural phenoHc polymer, lignin, which also is frequentiy present ia the cell wall of the fiber thus vegetable fibers are also often referred to as lignocellulosic fibers, except for cotton which does not contain lignin. 

The actual processes of uptake of chemical species by an organism typically encompass transport in the medium, adsorption at extracellular cell wall components, and internalisation by transfer through the cell membrane. Each of these steps constitutes a broad spectrum of physicochemical aspects, including chemical interactions between relevant components, electrostatic interactions, elementary chemical kinetics (in this volume, as pertains to the interface), diffusion limitations of mass transfer processes, etc. 

Cellulose is the primary structural component of the cell wall and, after removal of lignin and various other extractives, it is also the primary structural component of paper. Chemically, it is a semicrystalline microfibrillar linear polysaccharide of /M,4-linked d-glucopyranose (Figure 2.6). 

Many of the physical, chemical and biological properties of wood can be understood by referring to the polymeric chemical constituents. In many cases of wood modification, these polymeric components are modified to some extent. The three structural polymeric components of the wood cell wall are cellulose, hemicellulose and lignin. There are many excellent texts describing the structure and function of these components, and only a brief account is given here. 

Rowell, R.M. (1984a). Penetration and reactivity of cell wall components. In The Chemistry of Solid Wood, Rowell, R.M. (Ed.). Advances in Chemistry Series, 207, American Chemical Society, pp. 175-210. 

Another major component of the cell membranes are the lipopolysaccharides, which are present as phospholipid bilayers. Following the death of bacteria, the biopolymers that constitute their cell walls and membranes become part of the detrital organic carbon pool. The great abundance of these biopolymers in seawater and the sediments is a reflection of their resistance to chemical degradation and the important role that bacterioplankton play in marine biomass production. 

Carbohydrates are among the most abundant constituents of plants, animals, and microorganisms. Polymeric carbohydrates function as important food reserves, and as stmctural components in cell walls. Animals and most microorganisms are dependent upon the carbohydrates produced by plants for their very existence. Carbohydrates are the first products formed in photosynthesis, and are the products from which plants S5mthesize their own food reserves, as well as other chemical constituents. These materials then become the foodstuffs of other organisms. The main pathways of carbohydrate biosynthesis and degradation comprise an important component of... 

Pharmacology Micafungin is a semisynthetic lipopeptide (echinocandin) synthesized by a chemical modification of a fermentation product of Coleophoma empetri F-11899. Micafungin inhibits the synthesis of 1,3- -D-glucan, an essential component of fungal cell walls, which is not present in mammalian cells. Pharmacokinetics ... 

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