Concept explainers
a. Consider the malate dehydrogenase reaction, which is part of the citric acid cycle:
malate + NAD+
In yeast mitochondria, where the pH= 8.1, this reaction is exergonic only at low oxaloacetate concentrations. Assuming a pH = 8.1, a temperature of 37o C, and the steady-state concentrations given below, calculate the maximum concentration of oxaloacetate at which the reaction will still be exergonic.
b. How would a drop in pH affect
c. How would an increase in intracellular malate levels affect
d. How would an increase in intracellular pyruvate levels affect
Want to see the full answer?
Check out a sample textbook solutionChapter 3 Solutions
Biochemistry: Concepts and Connections (2nd Edition)
- a. Some of the acetyl-CoA used in the citric acid cycle is produced from pyruvate. List the reactants and products of this reaction. The reactants are pyruvate and The products are acetyl-CoA and In the process, a(n) is to b. Name an enzyme complex that catalyzes this reaction and list its negative effectors. is the enzyme complex that catalyzes this reaction. Its negative effectors are andarrow_forwardA. Explain why it is important that an energy producing pathway contains at least one regulatory enzyme, you can use either glycolysis or TCA enzymes to discuss this answer B. The first step in glycolysis involves the conversion of glucose to glucose-6- phosphate. Briefly explain how this reaction occurs as it is an endergonic reaction. C. Why is it important that the cell has a number of different high-energy biomolecules?arrow_forwardGiven the following information, calculate the physiological ΔG of the isocitrate dehydrogenase reaction at 25°C and pH 7.0: [NAD+]/[NADH] = 8, [α-ketoglutarate] = 0.1 mM, and [isocitrate] = 0.02 mM. Assume standard conditions for CO2 (ΔG°′ is given in Table). Is this reaction a likely site for metabolic control?arrow_forward
- Describe the mechanism of a-chymotrypsin. Explain the roles of constituents of the catalytic triad, their modes of catalysis, and the significance of the oxyanion hole in the catalysis.arrow_forwarda. Calculate how many carbons from an original glucose molecule will enter into the TCA cycle? (please provide your answer in number like 1, 2, 3) b. Based on the question you answered above what happens to the carbons that do not enter the cycle (write what it converts into)?arrow_forwarda. Use the values in Problem 23.31 to calculate the energy change in the following reaction. fructose 1,6-bisphosphate + ADP--------> fructose 6-phosphate + ATP b. Is this reaction energetically favorable or unfavorable? c. Write this reaction using curved arrow symbolism. d. Can this reaction be used to synthesize ATP from ADP? Explain.arrow_forward
- A. Using a simplified series of diagrams describe how a cell can extract 38 molecules of ATP(net)from one molecule of glucoses. B.What is the difference between aerobic and anaerobic respiration? How is fermentation different from both of them? Discuss two common fermentations that we use to make everyday useful products.arrow_forwardGive the systematic names and the first three digits in the E.C. classifications of the enzymes catalysing the following reactions:arrow_forwarda. Arachidic acid is shown in the diagram below. How many rounds of β-oxidation will be needed to fully catabolize arachidic acid? b. What products will be obtained from the complete β-oxidation of arachidic acid? c. What will be the final ATP output (after TCA cycle and oxidative phosphorylation) obtained from the complete β-oxidation of arachidic acid?arrow_forward
- a) describe the overall reaction catalyzed by the pyruvate dehydrogenase Situational Problems I. Oxidative decarboxylation of pyruvate and the TCA cycle in muscles are stimulated by increased aerobic excrcise. These processes operate only when O, is present, although oxygen does not participate directly in these processes. Explain why oxidative decarboxylation of pyruvate is activated under aerobic conditions. For the answer: a) describe the overall reaction catalyzed by the pyruvate complex (PDH) and its regulation; b) outline the intermediates and enzymes of the TCA cycle; c) explain the relationship between the reactions of PDH and the TCA cycle and the respiratory chain.arrow_forwardArrange the balanced biochemical equations for all the reactions in the payoff phase of glycolysis and the conversion of pyruvate to lactate.arrow_forward5. You discover a new cysteine protease similar to papain. Cysteine proteases are proteolytic enzymes that utilize a cysteine residue in the active site for the nucleophilic attack of a peptide bond, while a second residue acts as a base for proton abstraction in the reaction (acid base catalysis). In this novel enzyme the pKa of the cysteine residue is significantly lowered by the active site environment to pKa=4. a. Knowing that the protease shows highest activity between pH 4-6, what could be the identity of the base residue acting as a in the reaction? Explain and write the expected mechanism for the reaction. SH онarrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage Learning