Metabolic pathways Adenosine triphosphate

To correlate embryonic arrests with the metabolic pathways, and especially to understand why cellular organelles first undergo chemical damages, biological investigations include evaluation of DNA, RNA, protein, glucose, lipid, and adenosine-5 -triphosphate (ATP) contents, whose fractions are extracted and isolated by modified Schneider methods. In particular,... 

Two important implications of the reactions described in Equations (5.1) and (5.2) are (i) that redox reactions play an important role in metabolic transformations, with the cofactors nicotinamide adenine dinucleotide (NAD+) acting as electron acceptor in catabolic pathways and nicotinamide adenine dinucleotide phosphate (NADPH) as electron donor in anabolism, and (ii) that energy must be produced by catabolism and used in biosyntheses (almost always in the form of adenosine triphosphate, ATP). 

Other nuclei, such as 13C or 31P, may be used to study other metabolite pools, or they can complement H-NMR to create more sophisticated NMR spectra. 13C-NMR provides a greater spectral range ( 200 ppm) than H-NMR ( 15 ppm). Although lower natural abundance of 13C (1.1%) yields lower sensitivity, it also provides an opportunity to use isotopic enrichment to trace specific metabolic pathways with enhanced sensitivity.4 31P can observe high-energy phosphate metabolites such as adenosine triphosphate. 

The two major metabolic pathways necessary for normal RBC metabolism are the hexose monophosphate shunt pathway, with its associated enzyme systems, and the Embden-Myerhof pathway of anaerobic glycolysis. The former is responsible primarily for maintaining Hgb in the rednced state and thns preventing the formation of methemoglobin, while the latter metabolizes glucose to lactic acid, which leads to adenosine triphosphate formation. 

An alcohol can react with phosphoric acid to produce a phosphate ester iphosphoester). When two phosphate groups are joined, the resulting bond is a phosphoric anhydride bond. These two functional groups are important to the structure and fimction o( adenosine triphosphate (ATP), the universal energy currency of all cells. Cellular enzymes can carry out a reaction between a thiol and a carboxylic acid to produce a thioester. This reaction is essential for the activation of acyl groups in carbohydrate and fatty acid metabolism. Coenz)une A is the most important thiol involved in these pathways. 

FIGURE 1A4-1 The cell biology of extracellular acidification. When a receptor is stimulated, signal transduction pathways are Induced. Adenosine triphosphate (ATP) consumption is then compensated by the increased uptake and metabolism of glucose, which results m an increase in the excretion of acid waste products. The extracellular acidification is measured by the LAPS. (From F. Hafner. Biosens. 8/betecfron., 2000. 15. 149. With permission.)... 

The major pathway by which P enters into organic combination in plants is through formation of adenosine triphosphate (ATP) (Chapter 11.3). The latter is generated during photosynthesis, and is required by numerous metabolic processes. Among these are the assimilation of N and S by the plant, the transport of various nutritional ions through cell membranes, and the production of plant starch and cellulose (Table 12.7). 

Figure 41.1 Synthetic and metabolic pathway of coenzyme A (CoA). ATP, adenosine triphosphate ADP, adenosine diphosphate AMP, adenosine monophosphate PPi pyrophosphate Pi, phosphate.

Figure 6.2 Outline of the metabolic pathway by which carbohydrates are degraded to industrial solvents (and lactic acid). The arrows do not necessarily indicate a single reaction step, nor does a single strain or species of an organism catalyse all the reactions. ATP, adenosine-5 -triphosphate ADP, adenosine-5 -diphosphate NAD, nicotinamide adenine dinucleotide NADH, reduced NAD HSCoA, coenzyme A...

Just as Nature can synthesize sugars from smaller carbon chains, there is a natural process called glycolysis (Fig. 22.22) that breaks down glucose into two molecules of a three-carbon compound called pyruvate. This chain-shortening pathway is a critical part of the metabolism that occurs in almost all organisms. Glycolysis provides cells with adenosine triphosphate (ATP) and NADH (p. 814). 

Fig. 15.2. Pathways of fructose metabolism. 15.4, Fructose-1-phosphate aldolase 15.5, fructose-1,6-diphosphatase 15.7, D-glycerate kinase. F-l-P, Fructose-1-phosphate F-6-P, fructose-6-phosphate F-l,6-DiP, fructose-1,6-diphosphate Glc-6-F, glucose-6-phosphate ATP, adenosine triphosphate ADP, adenosine diphosphate...

The coenzyme adenosine triphosphate (ATP) acts as the central link between energy-yielding metabolic pathways and energy expenditure on physical and chemical work. The oxidation of metabolic fuels is linked to the phosphorylation of adenosine diphosphate (ADP) to adenosine triphosphate (ATP), while the expenditure of metabolic energy for the synthesis of body constituents, transport of compounds across cell membranes and the contraction of muscle results overall in the hydrolysis of ATP to yield ADP and phosphate ions. The total body content of ATP + ADP is under 350 mmol (about 10 g), but the amount of ATP synthesized and used each day is about 100 mol — about 70 kg, an amount equal to body weight. 

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