Metabolic energy transformation

Metabolic rate, basal (BM) Metabolic energy transformation calculated from measurements of heat production or oxygen consumption in an organism in a rested, awake, fasting, and thermoneutral state, in W nr. ... 

Vitamin An organie eompound present in variable, minute quantities in natural foodstuffs, and essential for the normal proeesses of growth and maintenanee of the body. Vitamins do not furnish energy, but are neeessary for energy transformation and for regulation of metabolism. 

In some cases, microorganisms can transform a contaminant, but they are not able to use this compound as a source of energy or carbon. This biotransformation is often called co-metabolism. In co-metabolism, the transformation of the compound is an incidental reaction catalyzed by enzymes, which are involved in the normal microbial metabolism.33 A well-known example of co-metabolism is the degradation of (TCE) by methanotrophic bacteria, a group of bacteria that use methane as their source of carbon and energy. When metabolizing methane, methanotrophs produce the enzyme methane monooxygenase, which catalyzes the oxidation of TCE and other chlorinated aliphatics under aerobic conditions.34 In addition to methane, toluene and phenol have been used as primary substrates to stimulate the aerobic co-metabolism of chlorinated solvents. 

Second, organisms may invest metabolic energy to synthesize reactive species. For example, before it is used to oxidize hydrocarbons, 02 is converted to a much more reactive oxidant by complexation and reducing it with a compound the organisms had to spend energy to make (see Section 17.3). This scheme is similar to one previously discussed in photochemical transformations where, by absorption of light, activated species are formed that are much more reactive (Chapter 16). 

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... 

The two alternative strategies of metabolism explored in active and sluggish fish therefore apply both to the divergence of energy metabolism and to the closely associated plastic metabolism, which provides normal functioning of energy transformation mechanisms. Active fish are characterized by more... 

Figure 3. Energy transformation half-cycles in fully coupled conservative metabolism. The catabolic half-cycle (k) is coupled to the ATP cycle (p, -p) which is itself coupled to anabolism (a) and work. These processes demand ATP, the energy for the transformation of which is supplied by the oxidation of glucose in the catabolic half-cycle. The system is irreversible so the net work is zero.

At any given instant in a cell, thousands of energy transformations are taking place. Energy is being extracted from fuels and used to power biosynthetic processes. These transformations are referred to as metabolism or intermediary metabolism. 

This example illustrates the essence of energy transformations and of metabolism itself energy released by carbon oxidation is converted into high phosphoryl-transfer potential. The favorable oxidation and unfavorable... 

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