Valonia cell

Highly crystalline 0-chitin is obtained from pogonophore tubes and the spines of certain diatoms, and is analogous in both crystallinity and morphology to the cellulose obtained from Valonia cell walls. Intensity data (10) were obtained for 61 observed non-meridional reflections for a specimen of dispersed (sonicated) crystallites of pogonophore tube (Oligobrachia... 

A cylindrical Nitella cell is 100 mm long and 1 mm in diameter, a spherical Valonia cell is 10 mm in diameter, and a spherical Chlorella cell is 4 im in diameter. 

The second choice is a simpler solution. According to Sarko and Muggli,66 all 39 observed reflections in the Valonia X-ray pattern are indexable by a two-chain triclinic unit cell with a = 9.41, b =8.15 and c = 10.34 A, a = 90°, 3 = 57.5°, and y = 96.2°. Ramie cellulose, on the other hand, is completely consistent with the two-chain monoclinic unit cell. Also, there are significant differences between their high-resolution solid-state l3C NMR spectra, indicating that Valonia and ramie celluloses, the two most crystalline forms, reflect two distinct families of biosynthesis. On this basis, the Valonia triclinic and the ramie monoclinic forms are classified69 as Ia and Ip, respectively. It has been shown from a systematic analysis of the NMR spectra by these authors, and from electron-dif-... 

Zimmerman, U., Steudle, E. Lelkes, P.I. (1976). Turgor pressure regulation in Valonia utricularis. Effect of cell wall elasticity and auxin. Plant Physiology, 58, 608-13. 

Lamellar, single crystals of ivory-nut mannan were studied by electron diffraction. The base-plane dimensions of the unit cell are a = 0.722 nm and b = 0.892 nm. The systematic absences confirmed the space group P212121. The diffraction pattern did not change with the crystallization temperature. Oriented crystallization ofD-mannan with its chain axis parallel to the microfibril substrates, Valonia ventricosa and bacterial cellulose, was discovered ( hetero-shish-kebabs ). 

Fibril arrangements in the cell wall of Valonia (12,000 X), (Electron micrograph from A. Frey-Wyssling and K. Miihlethaler, Ultrastructural Plant Cytology, Elsevier Science Publishers, Amsterdam, 1965, p. 298. Reprinted with permission from Elsevier Science Publishers.)... 

Cellulose is insoluble in water because of the high affinity of the polymer chains for one another. Its individual polymeric chains have molecular weights of 50,000 or greater. The molecular chains of cellulose interact in parallel bundles of about 2,000 chains. Each bundle constitutes a single microfibril. Many microfibrils arranged in parallel constitute a macrofibril, which can be seen under the light microscope. Figure 12.10 shows the inner cell walls of the plant Valonia the fibrils in the wall are almost pure cellulose. 

T ine structural studies on woody cell walls attacked by ectoenzymes of fungi in situ are numerous (cf. 1,2). In contrast, investigations on the selective degradation of cell walls by enzymes isolated from fungi are few. Jutte and Wardrop (3) attempted the use of crude commercial cellu-lase preparations to determine the degradation pattern of Valonia cellulose and beechwood fibers. Similar use of commercial preparations of enzymes was made by Reis and Roland (4) to evaluate the nature of diverse cell walls and to show the distribution of polysaccharides. An endo-/ -l,4-xylanase with specific xylanolytic activities was isolated from a commercial cellulase preparation using chromatographic methods and... 

C. If it takes 1 s for the internal concentration of ethanol, which is initially absent from the cells, to reach half of the external concentration for Chlorella, how long would it take for Nitella and Valonia Assume that ethanol is the same for all of the cells. 

Figure 6. Potential difference across cell wall in the (large) green photosynthesizing alga Valonia utricularis as a function of temperature. Note abrupt changes near 15° and 29°C. (From Drost-Hansen and Thorhaug, 1967).

Fig. 2.—Cellulose Microfibrils from Valonia macrophysa. (The purified cell-wall was mechanically dispersed in distilled water, dried, and shadowed. Note the tabular shape and the compound nature of the microfibrils.)...

Fig. 7.—Schematic Diagram Showing the Interrelationship of Base-plane Packing for Three Unit cells of Native Cellulose. (The one in heaviest outline is the Meyer-Misch cell. The cell proposed for Valonia cellulose is twice as large in the base-plane dimensions. The third cell, having a angle of 93°14 is another proposal. )...

Cellulose I is natural cellulose as found in cotton, wood, and Valonia. Although the Meyer and Misch structure (unit-cell dimensions a = 8.35,... 

Electron-diffraction measurements on cellulose microfibrils from Valonia show that the reciprocal-lattice points can be indexed, not by a Meyer-Misch unit cell, but by a unit cell having a and c periods twice as long. - This finding has been confirmed, and it is suggested that, although bacterial cellulose probably has the same unit cell, other native celluloses might differ. 

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