Scattered leaf arrangements

Figure 8-12. (a) The scattered leaf arrangement (phyllotaxis) of Plantago media (drawing by Ferenc Lantos, Pecs). Fibonacci numbers of spirals in the patterns of (b) Scales of a pinecone and (c) A cactus in Hawaii (b and c, photographs by the authors). 

Figure 8-12. The scattered leaf arrangement (phyllotaxis) of Phntago media.

Work on tRNA yields a of 23-2.5 nm by X-ray scattering. Many of the earliest studies predated the crystal structure determination of tRNA in 1974 [347-355] and thus attempted to elucidate its overall shape on the basis of the clover-leaf base-pairing model from sequence data. Open structures were discarded in favour of more compact schemes. Many folded structures were, however, compatible with the experimental data, while a simple triaxial body was not. The observation of two distinct i xs values led to the development in 1970 of a model with one large and two small ellipsoids whose main axes are parallel to one another and are arranged in an L-shape [353], and which anticipated the L-shape determined by crystallography (Fig. 26). Other studies on tRNA have investigated its melting... 

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