The Complete Oxidation of Glucose

The pentose phosphate pathway, present in the cytosol, can account for the complete oxidation of glucose, producing NADPH and COj but not ATP. 

THE COMPLETE OXIDATION OF GLUCOSE REQUIRES TRICARBOXYLIC ACID (TCA) CYCLE ACTIVITY 543... 

Cerebral metabolic rate declines from developmental levels and plateaus after maturation. Reliable quantitative data on the changes in cerebral circulation and metabolism in humans from the middle of the first decade of life to old age have been reported [2,39,44]. By 6 years of age, cerebral blood flow and oxygen consumption already have attained high rates, and they decline thereafter to the rates of normal young adulthood [45]. Oxygen is utilized in the brain almost entirely for the oxidation of carbohydrates [46]. The equation for the complete oxidation of glucose is ... 

Given that the maximum energy liberated from the complete oxidation of glucose to C02 and H20) is 2866kJ/mol and that the molecular weight of glucose is 180... 

These points can be better appreciated by comparing the complete oxidation of glucose with that of a typical saturated fatty acid, palmitate. 

These processes are, of course, more complex than this details are presented in this and other chapters. In brief, there are three phases for the complete oxidation of glucose and fatty acids ... 

The ATP required by the human brain is obtained from the complete oxidation of glucose it requires about 4 g of glucose per hour. If the same amount of ATP were to be generated from the conversion of glucose to lactate, approximately 60 g per hour would be required (i.e. almost 1.5 kg of glucose each day). 

The principles of oxidation-reduction energetics described above apply to the many metabolic reactions that involve electron transfers. For example, in many organisms, the oxidation of glucose supplies energy for the production of ATP. The complete oxidation of glucose ... 

A quantitatively much more important pathway of C02 fixation is the reductive pentose phosphate pathway (ribulose bisphosphate cycle or Calvin-Benson cycle Fig. 17-14). This sequence of reactions, which takes place in the chloroplasts of green plants and also in many chemiautotrophic bacteria, is essentially a way of reversing the oxidative pentose phosphate pathway (Fig. 17-8). The latter accomplishes the complete oxidation of glucose or of glucose 1-phosphate by NADP+ (Eq. 17-48) ... 

Each turn of the TCA cycle generates three molecules of NADH. In glycolysis the oxidation of glucose produces two molecules of pyruvate therefore, the complete oxidation of glucose requires two turns of the TCA cycle, to generate six molecules of NADH. Each molecule of NADH is oxidised by the mitochondrial respiratory chain to generate approximately three molecules of ATP, and so from the NADH alone, approximately 18 molecules of ATP can be formed per molecule of glucose. 

Table 18.4. ATP yield from the complete oxidation of glucose...

The major fuel for most organs is fatty adds. Events that conln l their liberation from triglycerides (T Gs) and their oxidation are described in subsequent sections of this chapter. A variety of control points encountered during the complete oxidation of glucose and of fatty acids to COj are revealed, A number of we -... 

Energy-Yielding Reactions in the Complete Oxidation of Glucose... 

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