Two biochemistry students are about to usemitochondria isolated from rat liver for an experiment on oxidative phosphorylation. The directions for the experiment specifyaddition of purified cytochrome c from any source to the reactionmixture. Why is the added cytochrome c needed? Why does thesource not have to be the same as that of the mitochondria?

Two biochemistry students are about to usemitochondria isolated from rat liver for an experiment on oxidative phosphorylation. The directions for the experiment specifyaddition of purified cytochrome c from any source to the reactionmixture. Why is the added cytochrome c needed? Why does thesource not have to be the same as that of the mitochondria?

Concepts of Biology

1st Edition

ISBN:9781938168116

Author:Samantha Fowler, Rebecca Roush, James Wise

Publisher:Samantha Fowler, Rebecca Roush, James Wise

Chapter4: How Cells Obtain Energy

Section: Chapter Questions

Problem 17CTQ: Both prokaryotic and eukaryotic organisms carry out some form of glycolysis. How does ha fact...

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When pure reduced cytochrome c is added to carefully prepared mitochondria along with ADP, Pi, antimycin A, and oxygen, the cytochrome c becomes oxidized, and ATP is formed, with a P/O ratio approaching 1.0.(a) Indicate the probable flow of electrons in this system.(b) Why was antimycin A added?(c) What does this experiment tell you about the location of coupling sitesfor oxidative phosphorylation?(d) Write a balanced equation for the overall reaction (including cyt c oxidation and ATP synthesis).(e) Calculate ΔG°′ for the above reaction, using E′0 values from Table 14.1and a ΔG°′ value for ATP hydrolysis of -32.2 kJ/mol.
In another key reaction in glycolysis, dihydroxyacetone phosphate (DHAP)is isomerized into glyceraldehyde-3-phosphate (GAP): Because ΔG°′ is positive, the equilibrium lies to the left.(a) Calculate the equilibrium constant and the equilibrium fraction of GAPfrom the above, at 37 °C.(b) In the cell, depletion of GAP makes the reaction proceed. What will ΔGbe if the concentration of GAP is always kept at 1/100 of the concentrationof DHAP?
Sonicating a suspension of mitochondria produces submitochondrial particles derived from the innermitochondrial membrane. These membranous vesicles seal inside out, so that the intermembrane space of themitochondria becomes the lumen of the submitochondrial particle. Explain (or diagram) the process of electrontransfer and oxidative phosphorylation in these particles. Assuming all the substrates for oxidativephosphorylation are present in excess, does ATP synthesis increase or decrease with an increase in the pH ofthe fluid in which the submitochondrial particles are suspended? Why?
Gluconeogenesis is a process that synthesize glucose from noncarbohydrateprecursors, which requires oxaloacetate as intermediates. The generation ofoxaloacetate only occurs in the mitochondria. For the species that has PEPCK inthe cytosol, briefly explain, with illustration, how oxaloacetate is transported out of the mitochondria to be used in gluconeogenesis.
When pure reduced cytochrome c is added to carefully prepared mitochondria along with ADP, P, antimycin A, and oxygen, the cytochrome c becomes oxidized, and ATP is formed, with a P/o ratio approaching 1.0. (a) Indicate the probable flow of electrons in this system. (b) Why was antimycin A added? (c) What does this experiment tell you about the location of cou- pling sites for oxidative phosphorylation? (d) Write a balanced equation for the overall reaction (including cyt c oxidation and ATP synthesis).
20.12 Classify the enzyme that catalyzes each of the following reactions: |3| a. CH3-C-COO + CO2 + ATP OOC-CH2-C-COO + ADP + P; + H b. CH3-CH2-OH + NAD* CH3-C-H + NADH + H*
Each of the cytochromes in the mitochondrion contains prosthetic groups. What is a prosthetic group? Which type of prosthetic group is associated with the cytochromes?
You are isolating mitochondria from insect cells and incubating in a test tube with 0.005 M FADH2, 0.05 M ADP and 0.05 M Pi. Assuming, these 3 can enter mitochondria at no cost,no glucose/products of glucose metabolism remain in the isolated mitochondria, and oxygen is present. Part 1) If all expected reactions go to completion, how much ATP is expected formed? (0 M)(0.02 M) (0.03 M) (0.05 M) (0.1 M) (0.005 M) (0.01 M) (0.015 M) Part 2) The ratio of FADH2/FAD at completion of all expected reactions would be? (2) (>>2) (0) (1) Part 3) After completion of all expected reactions, ratio of H ion concentration inside vs. outside the mitochondrial inner membrane should be? (<1) (~1) (>1)(0) Please provide brief explanation
When pure reduced cytochrome c is added to carefully prepared mito- chondria along with ADP, P, antimycin A, and oxygen, the cytochrome c becomes oxidized, and ATP is formed, with a P/O ratio approaching 1. Why was antimycin A added, and what does this experiment tell you about the location of coupling sites?
What is the total number of H+ transferred from matrix to intermembrane space of the mitochondria by complexes I, II and III for every 2 electrons movement? What would be the total amount of ATP synthesized (explain)?
A newly identified bacterium is unable to synthesize ubiquinone. A mobile electron carrier called CXC3 is used as a substitute. From the information provided in the table, calculate the delta G knot prime and the Keq value at 298 K for the redox reaction that occurs in this bacterium’s electron transport chain. Explain the impact that using CXC 3 instead of ubiquinol will have on ATP production in the cell. How might this cell adapt to this situation?
Why is the enzyme-catalyzed introduction of carbon–carbon double bonds into fatty acids called an electron transport system?