ATP yield from complete oxidation of glucose

TABLE 19-5 ATP Yield from Complete Oxidation of Glucose... 

As a comparison, note that 32 moles of ATP can be obtained from the complete oxidation of one mole of glucose but glucose contains 6, rather than 18, carbon atoms. Three glucose molecules contain 18 carbon atoms, and a more interesting comparison is the ATP yield from the oxidation of three glucose molecules, which is 3 X 32 = 96 ATP for the same number of carbon atoms. The yield of ATP from the oxidation of the lipid is still higher than that from the carbohydrate, even for the same number of carbon atoms. The reason is that a fatty acid is all hydrocarbon except for the carboxyl group that is, it exists in a... 

Palmitoyl-CoA would be processed by steps 1 to 4 of the cycle seven times (Table 15.1). The maximum yield of energy as ATP from the P-oxidation of a fatty acid can be calculated as shown in Table 15.2. One molecule of palmitate will yield 129 molecules of ATP. Compare this yield with that from complete oxidation of glucose (Table 12.1). For... 

When grown under aerobic conditions, the yeast produces two ATP molecules from one molecule of glucose by substrate-level phosphorylation in glycolysis. The two molecules of pyruvate produced can then be completely oxidized to CO2, and each yields a further 15 molecules of ATP. This leads to a slow decrease in the concentration of glucose, a steady production of CO2, and relatively little change in the amount of ATP. Also, the two molecules of NADH can be reoxidized to NAD+ by the electron-transport system. (This produces yet more ATP, as discussed in Chap. 14.)... 

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

Recall How does the yield of ATP from complete oxidation of one molecule of glucose in muscle and brain differ from that in liver, heart, and kidney What is the underlying reason for this difference ... 

Estimate the net yield of ATP from the complete oxidation of glucose, taking into account the different shuttles for the cytoplasmic reducing equivalents of NADH. Discuss the sources of uncertainty in the estimation. 

It is instructive to compare the energy yield from the complete oxidation of fatty acids with that obtained from an equivalent amount of glncose becanse both are important constituents of the diet. In Section 13.8, we saw that the oxidation of a single glucose molecule produces 32 ATP molecules. The complete oxidation of three 6-carbon glucose molecules... 

Calories (kcal). Since 38 ATP are derived from the complete oxidation of glucose, 304 Calories (kcal) of energy are formed (38 X 8 = 304). Under ideal conditions, the oxidation of glucose yields 686 Calories (kcal). Hence, the human body is 44% efficient in converting glucose to energy (304 686 x... 

Energy Balance of the Aerobic Carbohydrate Breakdown. Up to the formation of pyruvate 1 mole of ATP and 1 of NADHa arise from each triose. Another mole of NAD is reduced during the oxidative decarboxylation of pyruvate to acetyl-CoA. Up to the formation of acetyl-CoA (employing the respiratory chain) 1 - - 2 X 3 = 7 ATP are stored. Complete oxidation of active acetate in the citrate cycle yields another 12 moles of ATP per triose, i.e. a total of 19 ATP per mole of triose or 38 per mole of glucose. 

We saw in Chapter 14 that the energy yield from the production of two molecules of pyruvate from one molecule of glucose in glycolysis is 2 ATP and 2 NADH. In oxidative phosphorylation (Chapter 19), passage of two electrons from NADH to 02 drives the formation of about 2.5 ATP, and passage of two electrons from FADH2 to 02 yields about 1.5 ATP. This stoichiometry allows us to calculate the overall yield of ATP from the complete... 

We can now estimate how many molecules of ATP are formed when glucose is completely oxidized to GO2. The number of ATP (or GTP) molecules formed in glycolysis and the citric acid cycle is unequivocally known because it is determined by the stoichiometries of chemical reactions. In contrast, the AT P yield of oxidative phosphorylation is less certain because the stoi chiometries of proton pumping, ATP synthesis, and metabolite-transport processes need not be integer numbers or even have fixed values. As stated earlier, the best current estimates for the number of protons pumped out of the matrix by NADH-Q oxidoreductase, Q-cytochrome c oxidoreductase, and cytochrome c oxidase per electron pair are four, two, and four, respectively. The synthesis of a molecule of ATP is driven by the flow of about three protons through ATP synthase. An additional proton is consumed in transporting ATP from the matrix to the cytoplasm. Hence, about 2.5 molecules of cytoplasmic ATP are generated as a result of the flow of a pair of electrons from NADH to O2. For electrons that enter at the level of Q-cytochrome c oxidoreductase, such as those from the oxidation of succinate or cytoplasmic NADH, the yield is about 1.5 molecules of ATP per electron pair, Hence, as tallied in Table 18.4, about 30 molecules of ATP are formed... 

As an example of the energy yield from p-oxidation, the balance sheet for ATP production when the sixteen-carbon-fatty acid palmitic acid is degraded by p-oxidation is summarized in Figure 23.8. Complete oxidation of palmitate results in production of 129 molecules of ATP, three and one half times more energy than results from the complete oxidation of an equivalent amount of glucose. 

---