The inhibitor X prevents coenzyme Q (Q) from participating in electron transfer in the electron transport chain. (a) Will the presence of X prevent electrons from NADH from passing through the electron trans- port chain? Explain why or why not. (b) Compound Y is a non-physiological reducing agent capable of directly reducing cytochrome cl in Complex III. Would oxygen consumption resume upon the addition of compound Y to mitochondria inhibited by inhibitor X? Be sure to explain your answer.

The reduction potentials of iron in each of the cytochromes in the electron transport complexesvary from 0.The reduction potentials of iron in each of the cytochromes in the electron transport complexes vary from 0.1 V to 0.39 V. Explain why these different values are necessary for the operation of this process

Consider ³H-labeled pyruvate (containing three ³H at C3) and ¹4C-labeled OAA (¹4C at C3) are added to a preparation of mitochondria in which pyruvate dehydrogenase and the citric acid cycle enzymes are functional. Assume the labeled compounds react to form citrate that is labeled with both ³H and ¹4C. Assume also that once label is lost from a citric acid cycle intermediate that it does not become reincorporated. lf oxaloacetate (OAA) 3H 3H 3H pyruvate (a) Show the distribution of ³H and ¹4C in the citrate that is initially formed from the ¹4C-labeled OAA and the 3H-labeled ACS-CoA.

15.13) The NADH that is produced by glycolysis is not able to pass through the inner mitochondrial membrane to enter the matrix region and undergo oxidative phosphorylation. Name the two processes in which the energy from NADH made in glycolysis can enter the mitochondrial matrix. ANSWER: 1) malate-aspartate shuttle 2) glycerol 3-phosphate shuttle EXPLANATION: Oxidative phosphorylation requires that NADH be located within the mitochondrial matrix. Since pyruvate oxidation/decarboxylation and the reactions of the citric acid cycle occur in the mitochondrial matrix, the NADH created in those processes can immediately undergo oxidative phosphorylation. The NADH that is produced by glycolysis is able to pass through the outer mitochondrial membrane and enter the intermembrane space; however, it is not able to pass through the inner mitochondrial membrane to enter the matrix region. In order for the energy from this NADH to be utilized, it must be processed through "NADH shuttles." The two…