Metabolism energy concept

The increase by 1/3 found in the value of unassimilated food energy in predatory fish is so substantial that it was proposed to introduce a special term (U) into the balance equation, to denote liquid excretion. In the literature, a concept of metabolized energy was adopted, implying assimilated energy (A) minus the liquid excretion energy (U) (Brody, 1945 Brett and Groves, 1979 Jobling, 1983). The basic equation would then be ... 

The limit cycle concept reveals a possible explanation of the specific sensitivity of biological systems to a weak external stimulus through the following mechanism the internal LC represents a storage of (metabolic) energy, which can be used to build up a signal, whereas the externally supplied field energy (with appropriate frequency and intensity) only causes the LC to collapse. 

Bile acids and their conjugates are transported in the liver by carrier processes which are largely not understood. It has been demonstrated that the process is dependent on sodium ions and requires metabolic energy. Papers of Anwer et al. [15], Kitani and Kanai [16] and Erlinger [17] summarize current concepts. 

PART II TRANSDUCING AND STORING ENERGY Chapter 14 Metabolism Basic Concepts and Design 229... 

The unification and direction which the P concept gave to metabolic studies led to its rapid and enthusiastic adoption by the new generation of biochemists starting work after the end of World War II. Kalckar suggested the contribution resonance stabilization might make to the distinction between the two classes of phosphate compounds. T.L. Hill and Morales (1951) identified ionization effects and electrostatic repulsion as further possible contributants to the net differences in free energy between products and reactants. 

The history of energy metabolism is a fascinating example of how progress depends alternatively on new concepts and, at other times, on new technology that allows elements of the problem to be revisited and objectively measured. 

The importance of these reactions to the energy metabolism of the bacteria was recognized in 1895 by Winogradsky, who first proposed the concept of chemiautotrophy. Because the nitrifying bacteria grow... 

CONTENTS Acknowledgments, Margery G. Ord and Lloyd A. Stocken. Introduction. Biochemistry Before 1900. Early Metabolic Studies Energy Needs and the Composition of the Diet. Carbohydrate Utilization Glycolysis and Related Activities. Aspects of Carbohydrate Oxidation, Electron Transfer, and Oxidative Phosphorylation. Amino Acid Catabolism in Animals. The Utilization of Fatty Acids. The Impact of Isotopes 1925-1965. Biochemistry and the Cell. Concepts of protein Structure and Function. Chronological Summary of Main Events Up to ca. 1960. Principal Metabolic Pathways. Index. 

Many fundamental concepts in modem biology have been established through studies on aquatic organisms. Fish are of special interest to research workers, because some of their metabolic features characterized early vertebrates. Fish have also evolved numerous adaptations, which have permitted them not only to survive but also to thrive in recent times. The range of structural and functional adaptations and metabolic flexibility, combined with individual specializations, has resulted in an immense diversity of fish - more than 20 000 species - which greatly exceeds that of amphibians, reptiles, birds and mammals. As the final link in many food chains, fish can be reliable indicators of the condition of complex ecosystems. Studies on fish provide an understanding of the pathways of metabolic substances and of energy transformations in bodies... 

Concepts of metabolic processes may be distorted if they are based solely on energy. We have already shown that protein production and the accumulation of lipids differ between the three races of European anchovy, but the energy equivalents of the body weights alter identically in all three (Shulman and Urdenko, 1989), even though the metabolic patterns differ. No fish farmer will consider only the caloric content of the feed, but will concentrate on a proper balance of constituents. Only considerations of both matter and energy will give a true understanding of all the processes involved. 

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