Microfibrils of cellulose

The superimposition of diffraction spots from both phases gives the previously reported pattern that was thought to require an eight-chain unit cell. In the la stmcture, because of its one-chain unit cell, all chains must have parallel packing. Since the la and ip stmctures exist in the same microfibril of cellulose, the chains in the ip stmcture should also be parallel. 

The primary cell-wall of plants is formed by microfibrils of cellulose in a complex matrix of polysaccharides, proteins, and glycoproteins. The structure and relationship of the different components is under continuous study and revision, and most of them can now be identified and their biosynthesis studied.124"126... 

Figure 2 Schematic representation of cellulose synthesis from Acetobacter xylinus (not to scale). Microfibrils of cellulose are secreted into the fermentation medium via terminal complex transmembrane synthetic sites. In the extracellular medium, a number of elementary microfibrils coalesce to form a flat, twisting and highly persistent ribbon of cellulose. The presence of polysaccharides in the fermentation medium allows interactions to occur both before and after the assembly of microfibrils into ribbons. The right angle bend at the point of ribbon assembly is purely schematic...

Fig. 19. Molecular model of a microfibril of cellulose, projected along the fibril axes compared with the typical morphologies observed for Valonia cellulose and tunicin, along with the CPK (Corey-PauUng-Koltun) representation of the main crystalline faces for cellulose 1. (See Color Plate 12.)...

Fig. 23. Computer representation of the crystalline morphology and surfaces of a microfibril of cellulose made up of 36 cellulose chains. (See Color Plate 13.)...

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