Anabolic and catabolic processes

The metabolism of microorganisms is complex. However, the metabolic pathways followed by anabolic and catabolic processes need to be described in simple terms to be applied for design and operation of urban wastewater systems. 

Explain the difference between anabolic and catabolic processes. 

The organic material is subjected to a variety of anabolic and catabolic processes, which are controlled by organisms. Metabolites of these processes can be released into the water as both, as POM and as dissolved organic material (DOM). Also in DOM, the amount of inorganic precursors is generally quantified as a sum of dissolved organic carbon, nitrogen or phosphorus (DOC, DON, DOP). As DOM is not subjected to... 

The relationship between anabolic and catabolic processes is illustrated in Figure 1.20. As nutrient molecules are degraded, energy and reducing power are conserved in ATP and NADH molecules, respectively. Biosynthetic processes use metabolites of catabolism, synthesized ATP and NADPH (reduced nicotinamide adenine dinucleotide phosphate, a source of reducing power, i.e., high-energy electrons), to create complex structure and function. 

Amphibolic pathways can function in both anabolic and catabolic processes. The citric acid cycle is obviously catabolic, because acetyl groups are oxidized to form C02 and energy is conserved in reduced coenzyme molecules. The citric acid cycle is also anabolic, because several citric acid cycle intermediates are precursors in biosynthetic pathways (Figure 9.10). For example,... 

Because nitrogen catabolic pathways are similar in many organisms and most research efforts in nitrogen catabolism have concentrated on mammals, the mammalian pathways are the focus of this chapter. Chapter 15 begins with a discussion of the pathways that degrade amino acids to form ammonia and the carbon skeletons used in anabolic and catabolic processes. This is followed by a discussion of urea synthesis. Chapter 15 ends with descriptions of the degradation of several amine neurotransmitters, the nucleotides, and the porphyrin heme. 

How are animals (or other multicellular organisms) able to maintain a balance between anabolic and catabolic processes as they respond and adapt to changes in their environment The answer to this question is not fully understood. However, various forms of intercellular communication are believed to play an important role. Most intercellular communication occurs by means of chemical signals. Once released into the extracellular environment, each chemical signal is... 

Throughout life, organisms strike a balance between anabolic and catabolic processes so that they can meet their metabolic needs as they respond to environmental changes. The information transfers that sustain living processes are managed largely by hormones. 

All metabolism is connected. This block diagram of intermediary metabolism shows the relationship between anabolic and catabolic processes and the common metabolites seen in many pathways. Sign in at www.thomsonedu.com/iogin to see an animated version of this figure. 

Both anabolic and catabolic processes include a vast number of different chemical reactions, albeit a number of common features. Most of the metabolic processes occur mainly in the cytoplasm, but can occur inside intracellular organelles, such as the mitochondria. Anabolic and catabolic reactions involve the action of enzymes and the utilization of energy. The metabolism of the whole body is controlled in an integrated fashion by the action of hormones and/or the nervous system. 

Photosynthesis is the process that provides energy to all anabolic and catabolic processes in ecosystems. The rate at which plants assimilate CO2 in the field may be quite different from optimal conditions in the test tube or in growth cabinets. The rate depends on the environmental conditions of the habitat which determine to what extent the genetic capability of a plant can actually be used for photosynthesis. The main factor restricting photosynthesis in the field is the availability of light. But, other factors my become just as rate 1imitating, such as atmospheric carbon dioxide concentration, air humidity and temperature, and water or nutrient supply from the soil. Time is an additional important factor which influences the carbon balance via plant age but also by deterimining the dose of stress. 

Little is known of the biosynthesis, breakdown, or role of sulfatides. Two observations seem established the biosynthesis of sulfatides coincides with the appearance of myelin and studies with the aid of a radioactive precursor have established a slow but definite turnover of sulfatides in the adult brain. Consequently, the brain constantly synthesizes and degrades sulfatides. Similar anabolic and catabolic processes are likely to occur in other tissues. 

On the other hand, the inhibitory effect of the excessive synthesis of vitamin B on the growth rate may be rationalized in terms of the competition for some common metabolites (Vorobjeva, 1976). A number of observations suggest the existence of a threshold level of vitamin B12 in the cell (1000 Lig/g biomass), above which competition with other anabolic reactions for common intermediates occurs, since some of them, such as ATP, NAD, FAD, are sources of the structural units of the vitamin Bn molecule. Probably, this is the reason why factors that delay growth and decouple the anabolic and catabolic processes lead to an increased vitamin Bi2 synthesis (Konovalova and Vorobjeva, 1970 Ibragimova and Sakharova,... 

The brief description given above on the construction of growth process equations is intended to give some idea of the overall aspects of what goes on when cells are grown. It is not necessary to go through the construction of anabolic and catabolic process equations if one is interested only in metabolism. Once the kinds and quantities of the organic reactants and products of metabolism are known (as... 

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