3. Now for the citric acid cycle, it is time to follow the carbons! Using labeled pyruvate: 14CH3¹3COCOO- trace the fate of that pyruvate 'when added to respiring mitochondria. a. After one turn of the citric acid cycle what is the location of each labeled carbon? Show this by drawing the structural formulas for the TCA intermediates. b. What is the consequence of the metabolism of succinate with respect to the labeled atoms? Cellular respiration can be studied in isolated mitochondria by measuring oxygen consumption under different conditions. If 0.01 M sodium malonate is added to actively respiring mitochondria that are using pyruvate as fuel source, respiration soon stops, and a metabolic intermediate accumulates. What is the name and structure of this intermediate? Why does it accumulate? What is sodium malonate doing and how? C. d. ( e. I Explain. Aside from removal of the malonate, how can this inhibition of respiration be overcome?

3. Now for the citric acid cycle, it is time to follow the carbons! Using labeled pyruvate: 14CH3¹3COCOO- trace the fate of that pyruvate 'when added to respiring mitochondria. a. After one turn of the citric acid cycle what is the location of each labeled carbon? Show this by drawing the structural formulas for the TCA intermediates. b. What is the consequence of the metabolism of succinate with respect to the labeled atoms? Cellular respiration can be studied in isolated mitochondria by measuring oxygen consumption under different conditions. If 0.01 M sodium malonate is added to actively respiring mitochondria that are using pyruvate as fuel source, respiration soon stops, and a metabolic intermediate accumulates. What is the name and structure of this intermediate? Why does it accumulate? What is sodium malonate doing and how? C. d. ( e. I Explain. Aside from removal of the malonate, how can this inhibition of respiration be overcome?

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter27: Metabolic Integration And Organ Specialization

Section: Chapter Questions

Problem 20P: Figure 27.3 illustrates the response of R (ATP-regenerating) and U (ATP-utilizing) enzymes to energy...

See similar textbooks

Similar questions

In the first step of the citric acid cycle, an acetyl group from acetyl CoA reacts with oxaloacetate to form (a) pyruvate (b) citrate (c) NADH (d) ATP (e) CO2
Figure 27.3 illustrates the response of R (ATP-regenerating) and U (ATP-utilizing) enzymes to energy charge. a. Would hexokinase be an R enzyme or a U enzyme? Would glutamine: PRPP amidotransferase, the second enzyme in purine biosynthesis, be an R enzyme or a U enzyme? b. If energy charge = 0.5: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low? c. If energy charge = 0.95: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low?
3. A recently discovered mutant yeast has a shorter glycolytic pathway, and with a new enzyme that catalyzes the reaction: Glyceraldehyde-3-P + H₂ + NAD+ ‒‒‒‒‒‒> 3-phosphoglycerate + NADH+H* Would shortening the glycolytic pathway in this way benefit the cell? Explain. Consider metabolic outcomes only in anaerobic conditions.
1. The citric acid cycle ends with the reaction catalyzed by malate dehydrogenase (MDH) shown below. The product of this reaction, oxaloacetate (OAA), combines with acetylCoA (catalyzed by citrate synthase) to begin the cycle. Given this answer the following questions. All of your work must be shown. R = 8.314 J mol-1 K -1 Malate + NAD* OAA + NADH a. What is the keq of the reaction given that AG" = 30.0 kJ/mol? Assume T = 298K. Please show your work. b. The concentration of malate within a rat mitochondria is about 0.20mM. Furthermore, the ratio of [NAD+]/[NADH] is around 10/1. Given this calculate the concentration of OAA within the mitochondria considering that the MDH reaction is at equilibrium under mitochondrial conditions. c. Citrate synthase catalyzes the first step in the CAC as shown below. Determination of its actual free energy change is difficult for a number of reasons however most scientist will point to the fact that it is negative. Let's assume AG = -5.0 kJ/mol. The…
1 what is the net reaction of the citric acid cycle? what happens to each product? 2 Starting with acetyl- CoenzymeA and oxaloacetate, draw out the molecular structures for each step of the citric acid cycle. For each step, include the name of the enzyme that catalyzes the reaction?
3. Trace the course of the radioactive label in 2-[14C] glucose through glycolysis and the citric acid cycle. At what points(s) in the cycle will the radioactivity be released as 14CO2? How many turns of the cycle will be required for complete conversion of the radioactivity to CO2? 4. Repeat problem 3 for pyruvate that is 14C-labeled at its methyl group.
10. The reaction for cellular respiration is exergonic (AG = -2870 kcal/mol) but only produces 32 ATP per molecule of glucose, representing an energy total of AG = +976 kcal/mol. What can explain this discrepancy? A. One molecule of glucose produces 2 pyruvate during glycolysis and cellular respiration therefore produces a total of 64 ATP. This makes up for the difference in energy converted from glucose to ATP. B. Both NADH and FADH₂ are also produced and contribute to some ATP, on top of the 32 ATP already produced. C. Energy remains in some glucose molecules that are not yet oxidized. D. Energy is lost in the form of heat. E. Cellular respiration includes some endergonic reactions that make up the difference in energy converted from glucose to ATP.
2. Formation of OAA in mitochondria. In the last reaction of the TCA cycle, malate is dehydrogenated to regenerate the OAA necessary for the entry of acetyl-coA into the cycle: L-Malate + NAD+ → OAA + NADH + H+ AGo = 30.0 kJ/mol (a) Calculate the equilibrium ponstant for this reaction at 25 C. b) Because AGo assumes a standard pH of 7, the equilibrium constant calculated in (a) corresponds to K'eg _JOAA][NADH] [L-malate][NAD*] The measured concentration of L-malate in rat liver mitochondria is about 0.2 mM when the ratio [NAD*] / [NADH] is 10. Calculate the concentration of OAA at pH 7 in these mitochondria. (c) To appreciate the magnitude of the mitochondrial OAA concentration, calculate the number of OAA molecules in a single rat liver mitochondrion. Assume the mitochondrion is a sphere of diameter 2.0 µm. (From problem 10, chapter 16)
2. The overall result of CH,OH + 2 NAD+ + 2 NADH glycolysis can be summarized by the equation on the right in which HO the glucose origins of the carbon atoms in pyruvate are color coded. Show by writing the reactions catalyzed by aldolase and triose phosphate isomerase and num- bering the carbons why this is the fate of glucose carbon atoms in pyruvate. Indicate numbering of carbons in Glucose-6-Pi, Fructose-1,6-BisPi, enzyme products, and pyruvate. HO + 2 Pi 2 + 2 ATP > OH + 2 ADP (CH3 + 2 H20 Glucose Pyruvate
3, Describe the process of oxidative phosphorylation, as completely as possible. In your description, include the terms NADH, FADH2, ATP, mitochondria (or mitochondrial), glycolysis, Kreb's cycle, electron (or electrons), proton (or protons), and oxygen. In your description, account for how ATP molecules get produced, and how many ATP molecules are produced per FADH2 and NADH (note: NADH from outside the mitochondria generate a different number of ATP compared to NADH inside the mitochondria.
1. Identify the oxidized coenzyme (letter abbreviation only) that participates in this reaction of the Kreb’s cycle. Succinate --> Fumarate 2. How many mol of NADH can be obtained upon the beta oxidation of stearic acid? 3. How many mol of ATP can be obtained upon the complete oxidation of 1 mol stearic acid? 4. How many steps in glycolysis in which ATO is converted to ADP?
2. Calculate the number of ATP molecules generated by the following net reactions of the citric acid cycle. Assume that all NADH and QH2 are oxidized to yield ATP, pyruvate is converted to acetyl CoA, and the malate-aspartate shuttle is operating. (a) 1 pyruvate –3 CO2 (b) Citrate Oxaloacetate + 2 CO2