Tally of the ATPs Produced

The number of ATPs produced by complete oxidation of a molecule of glucose can be calculated at this point This calculation is not directly relevant to determination of the energy requirement. NADH from the Krebs cycle is responsible for the production of many more ATPs than is glycolysis. In glycolysis, an ATP is expended at the points of hexokinase and phosphofmetokinase. For each molecule 

FIGURE 5.4 One molecule of water is involved in the hydrolysis and synthesis of ATP, Continued synthesis of ATP during the course of the day docs not result in net production of water in the body This is because ATP is continuously hydrolyzed over the course of the day when it participates in ATP-requiring reactions. 

TABLE 5.2 Points tn Glycolysis and the Krebs Cycle ot which Cofactors Are Reduced and Carbon Diovide Is Released 

Enzyme MADH 4 H-orFADHj produced per f lucvse COj prwiuood 

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Electron Transport and ATP Production Tally of the ATPs Produced... 

This also produces an NADH, providing another 2.5 ATP s. thus the final tally is -4 + 2.5 + 2.5 = +1 ATP to produce one urea from two amino acid nitrogens. Of course for mammals this does not take into account the physiological costs of excreting the urea, which can be significant. 

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