BIOL 2080 Chapter 2: Chapter 2 The Plant Cell
25 Mar 2016
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Document Summary
Cell wall encloses all other parts of the plant cell, collectively called the protoplast. Cell wall material is formed by protoplast. Plant cell wall may consist of one or two layers. Primary wall: first layer, formed early in life od a plant cell, composed of polysaccharides, particularly cellulose, cellulose is in the form of fibrils, extremely fine fibers, fibrils are embedded in a matrix of other polysaccharides. Secondary wall: internal to primary wall, lignin, a very complex organic molecule, is a major component of the cell walls, in addition to the cellulose and other polysaccharides. Cellulose is the most abundant organic compound, with lignin not far behind. Only certain types of plants have secondary cell walls: usually those specialized for support, protection, or water conduction. Lignin is known for its toughness: gives wood its characteristic strength, provides protection against attack by pathogens and consumption by herbivores. Cell wall is not a solid structure: minute pores, or pits, exist.
