Oxidation energy yield

Group 1 catabolism, oxidative, energy-yielding. Group 2 anabolism, reductive, energy-requiring. 

Optimum Mixture A specific mixture of fuel and oxidant that yields the most rapid comhustion at a specific measured quantity or that yields the lowest value of the minimum ignition energy or that produces the maximum deflagration pressure. The optimum mixture is not always the same for each comhustion property that is measured. 

Nitrification consists of two energy yielding steps the oxidation of ammonium to nitrite, and the oxidation of nitrite to nitrate. These equations are generally represented as follows ... 

In most tissues, where the primary role of the citric acid cycle is in energy-yielding metabohsm, respiratory control via the respiratory chain and oxidative phosphorylation regulates citric acid cycle activity (Chapter 14). Thus, activity is immediately dependent on the supply of NAD, which in turn, because of the tight couphng between oxidation and phosphorylation, is dependent on the availabihty of ADP and hence, ulti-... 

Table 27-1. Energy yields, oxygen consumption, and carbon dioxide production in the oxidation of metabolic fuels.

Thiamin has a central role in energy-yielding metabo-hsm, and especially the metabohsm of carbohydrate (Figure 45-9). Thiamin diphosphate is the coenzyme for three multi-enzyme complexes that catalyze oxidative decarboxylation reactions pymvate dehydrogenase in carbohydrate metabolism a-ketoglutarate dehydro-... 

Safety considerations are paramount in any boron hydride synthesis. The energy yield from the oxidations of boron hydrides is too high for any cavalier treatment of boron hydrides. Exclusion of air is the critical consideration in diborane reactions. Decaborane(14) is less reactive, generally, in a kinetic sense, but the thermodynamic potential is comparable. In addition, all volatile boron hydrides are toxic. The procedures described in the latter two preparations are within our experience non-hazardous. These procedures should be followed in every detail improvisation is not recommended. 

Taking sulfide oxidation (Reaction 22.19) as an example, when the fluid mixture reaches 25 °C, there are about 5 mmol of H2S(aq) and 0.6 mmol of 02(aq) in the unreacted fluid, per kg of vent water. The 02(aq) will be consumed first, after about 0.3 mmol of reaction turnover, since its reaction coefficient is two it is the limiting reactant. The thermodynamic drive for this reaction at this temperature is about 770 kJ mol-1. The energy yield, then, is (0.3 x 10-3 mol kg-1) x (770 x 103 J mol-1), or about 230 J kg-1 vent water (Fig. 22.8). In reality, of course, this entire yield would not necessarily be available at this point in the mixing. If some of the 02(aq) had been consumed earlier, or is taken up by reaction with other reduced species, less of it, and hence less energy would be available for sulfide oxidation. 

Upon burial in the sediments, organic matter is microbially oxidized in a sequence dictated by the Gibbs Free Energy yield of each reaction (Froelich et at., 1979). The oxidants are used in this sequence respiration of oxygen,... 

The free energy yield (AG ) per mole CH2O oxidized can be computed for this reaction by substituting into Eq. 7.29. as follows ... 

Many of the chemical reactions that occur in sediments during diagenesis are mediated by marine organisms or are a consequence of biotic activities. Most are energy-yielding redox reactions driven by the oxidation of organic matter and, hence, represent a critical metabolic resource to benthic organisms. 

Marine nitrifiers tend to be slow growers compared to heterotrophs. This reflects the relatively low energy yield from ammonia oxidation. The nitrifiers tend to be photoin-hibited, making them less likely to compete with the photoheterotrophs for O2. While O2 is a requirement, some nitrifiers are capable of growing under suboxic conditions. 

By combining the glycolytic pathway, the Krebs cycle, and oxidative phosphorylation, the energy yield from the aerobic degradation of glucose will be... 

The higher energy yield per carbon atom from fatty acid compared with carbohydrate reflects its higher level of reduction, which consequently allows more oxidation. Thus, fat is logically the preferred storage molecule to carbohydrate. This is... 

By means of this additional step, the -oxidation process can then continue as normal. The energy yield will be only slightly less than that for stearoyl-CoA, since there is omission of transfer of one pair of hydrogen atoms to FAD, and consequently loss of 2 mol ATP. 

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