### Inhibitors of Oxidative PhosphorylationCyanide, oligomycin, and 2,4-dinitrophenol are all inhibitors of oxidative phosphorylation in mitochondria. Below are explanations for the effects of these inhibitors under specific conditions.#### (a) ATP Synthesis and Cyanide InhibitionWhen cyanide is added to an active in vitro suspension of mitochondria, it blocks ATP synthesis. This occurs because cyanide inhibits cytochrome c oxidase, a component of the electron transport chain (ETC), preventing electron transfer and thus proton pumping necessary for ATP production.**Question:** - What happens to the rate of ATP synthesis when 2,4-dinitrophenol is added to this mitochondrial suspension after it was treated with cyanide?**Explanation:**- Since cyanide has already inhibited electron flow in the ETC, adding 2,4-dinitrophenol will not affect ATP synthesis further, as there is no proton gradient to dissipate.#### (b) Oxygen Consumption and Oligomycin InhibitionOligomycin decreases the rate of oxygen consumption in an in vitro suspension of mitochondria by inhibiting ATP synthase. This prevents protons from flowing back into the mitochondrial matrix, halting the ETC.**Question:** - What happens to the rate of oxygen consumption in this oligomycin-inhibited system after adding 2,4-dinitrophenol?**Explanation:**- Adding 2,4-dinitrophenol uncouples oxidative phosphorylation by dissipating the proton gradient, allowing the ETC to proceed and increase oxygen consumption even though ATP synthesis remains inhibited.

ETC consists of four protein complexes called Complex I, II, III and IV that transport electrons…

Answered: 1. Cyanide, oligomycin, and…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

Intramitochondrial ATP concentrations are about 5 mM, and phos- phate concentration is about 10 mM. If ADP is five times more abundant than AMP, calculate the molar concentrations of ADP and AMP at an energy charge of 0.85. Calculate AG for ATP hydrolysis at 37 °C under these conditions. The energy charge is the concentra- tion of ATP plus half the concentration of ADP divided by the total adenine nucleotide concentration: [ATP] + 1/2[ADP] [ATP] + [ADP] + [AMP]
Citrate and isocitrate are interconverted via the enzyme aconitase: The standard free energy change for this reaction is +6.7 kJ/mol. In my pet llama's mitochondria, the free energy change was measured to be +0.8 kJ/mol. (No llamas were harmed in this experiment!) a. Calculate the [isocitrate]/[citrate] ratio in these mitochondria. b. If [isocitrate] =0.03 mM, what is [citrate]?
Focusing on the mechanism linking complex I and ATP synthase depicted in figure 3 in the article, compare that hypothetical mechanism to the classical presentation described in our textbook. What are the major differences between this mechanism and Peter Mitchel’s original chemiosmotic theory? What are the similarities.
Consider the malate dehydrogenase reaction from the citric acid cycle. Given the listed concentrations, calculate the free energy change for this reaction at energy change for this reaction at 37.0 ˚C (310 K). AG' for the reaction is +29.7 kJ/mol. Assume that the reaction occurs at pH 7. [malate] = 1.45 mM AG: [oxaloacetate] = 0.130 mM [NAD+ ] = 110 mM [NADH] = 44 mM 47.06 Incorrect kJ.mol-1
The amount of glucose 6-phophate that is used by the glycolytic or pentose phosphate (b) pathways is determined by the current metabolic state of the cytosol. This regulation is achieved in part via allosteric regulation of the first committed step of the pentose phosphate pathway. (i) What metabolite is the key allosteric regulator of the pentose phosphate pathway, and what enzyme does this metabolite regulate? (ii) What happens to glucose 6-phopshate in the limiting case when this metabolite is in excess? (iii) What happens to glucose 6-phophate in the limiting case when this metabolite is absent?
1. (a) The reaction catalyzed by citrate synthase is the first step of the TCA cycle. In glycolysis, two key reactions to produce ATP occur because an unfavorable reaction is coupled to another reaction that is thermodynamically favorable. The reaction catalyzed by citrate synthase is similarly coupled to an unfavorable reaction in the TCA cycle. Write the unfavorable TCA reaction using structural formulas and write the key step that drives the two coupled reactions forward. What is the overall AG" of the coupled reactions? (b). K(yM) 25.7 Inhibitor Bromoacetyl-CoA ATP NADH 6800 8300 The inhibitor constants for three inhibitors of por- cine citrate synthase are summarized in the table on the right. The compounds were all determined to bind in the ac- tive site as competitive inhibitors of acetyl-CoA. Because they bind as competitive inhibitors, all three inhibitors must exhibit structural similarity to some part of acetyl-CoA. Look up in the textbook the structural formulas for…
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.
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…
For the following enzymes (3-6) predict how the conditions will most likely affect the enzymes activity with one of the following and provide a 1 sentence explanation: a. increase activity b. decrease activity c. not likely to alter activity 3) alpha-ketoglutarate dehydrogenase complex binding to AMP when [AMP] is high. 4) phosphohexose isomerase binding NADH when [NADH] is high 5) phosphofructose-1 binding NAD+ when [NAD+] is high 6) pyruvate dehydrogenase complex binding to ATP when [ATP] is high
Consider a 24:1 △cis-9 fatty acid in the mitochondrion. For each fatty acid given, determine the following. 1. Gross ATP from b-oxidation cycles 2. Gross ATP from acetyl CoA produced 3. Gross ATP from conversion of propionyl CoA (if applicable) 4. Total number of ATP deducted 5. Total net ATP
To carefully prepared mitochondria were added succinate, oxidized cytochrome c, ADP, orthophosphate, and sodium cyanide. The overall balanced equation is: succinate + 2 cyt c(ox) + ADP + Pi --> fumarate + 2 cyt c(red) + ATP + H2O The standard state free energy of this system is O -10.3 kJ/mol 42.5 kJ/mol O 10.3 kJ/mol -42.5 kJ/mol
We have described an ATP synthase complex with an Fo complex of 9 c-subunits. Consider if the F0 complex had 12 c- subunits instead of only 9 (assume a eukaryote). What would be the P/O ratio (the ATP produced in the cytosol per atom of O reduced (or a pair of e- if you want to think of it that way) obtained from using B-hydroxy-fatty-acyl-CoA Dehydrogenase? (report to 1 decimal place) ATP

SEE MORE QUESTIONS

Recommended textbooks for you

Biochemistry

ISBN:

9781319114671

Author:

Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:

W. H. Freeman

Lehninger Principles of Biochemistry

Biochemistry

ISBN:

9781464126116

Author:

David L. Nelson, Michael M. Cox

Publisher:

W. H. Freeman

Fundamentals of Biochemistry: Life at the Molecul…

Biochemistry

ISBN:

9781118918401

Author:

Donald Voet, Judith G. Voet, Charlotte W. Pratt

Publisher:

WILEY

Biochemistry

ISBN:

9781319114671

Author:

Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:

W. H. Freeman

Lehninger Principles of Biochemistry

Biochemistry

ISBN:

9781464126116

Author:

David L. Nelson, Michael M. Cox

Publisher:

W. H. Freeman

Fundamentals of Biochemistry: Life at the Molecul…

Biochemistry

ISBN:

9781118918401

Author:

Donald Voet, Judith G. Voet, Charlotte W. Pratt

Publisher:

WILEY

Biochemistry

ISBN:

9781305961135

Author:

Mary K. Campbell, Shawn O. Farrell, Owen M. McDougal

Publisher:

Cengage Learning

Biochemistry

ISBN:

9781305577206

Author:

Reginald H. Garrett, Charles M. Grisham

Publisher:

Cengage Learning

Fundamentals of General, Organic, and Biological …

Biochemistry

ISBN:

9780134015187

Author:

John E. McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson

Publisher:

PEARSON

SEE MORE TEXTBOOKS