The maintenance of a proton motive force across the inner mitochondrial membrane is crucial for continued ATP production. Surprisingly, it has been discovered that the inner membranes of certain cells contain proteins, called uncoupling proteins, that are capable of transporting protons from the intermembrane space to the mitochondrial matrix. Why would mitochondria contain transporters that essentially waste energy potential in the proton gradient?

The maintenance of a proton motive force across the inner mitochondrial membrane is crucial for continued ATP production. Surprisingly, it has been discovered that the inner membranes of certain cells contain proteins, called uncoupling proteins, that are capable of transporting protons from the intermembrane space to the mitochondrial matrix. Why would mitochondria contain transporters that essentially waste energy potential in the proton gradient?

Name: The maintenance of a proton motive force across the inner mitochondria
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Description: The maintenance of a proton motive force across the inner mitochondrial membrane is crucial for continued ATP production. Surprisingly, it has been discovered that the inner membranes of certain cells contain proteins, called uncoupling proteins, tha

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter2: Cell Physiology

Section: Chapter Questions

Problem 10RE: Using the answer code on the right, indicate which form of energy production is being described: 1....

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The majority of ATP production in aerobic cellular respiration occurs within the mitochondria during electron transport. In this phase of cellular respiration, NADH and FADH, are oxidized to become NAD+ and FAD+. The protons and electrons released during this axidation are used to establisha chemiosmotic gradient in the mitochondrial intermembrane space. The potential established by this gradient is used to convert mechanical energy into the chemical energy needed to join an inorganic phosphate on to ADP, thus creating ATP. Mitochondrial DNA Lamela er membrane Inner boundary membrane - Cristal membrane Matrin- Cristae Matrix granule Ribosome ATP synthase Intermembrane space Intracristal space Peripheral space Outer membrane Parins Mitochondrion structure by Kelvin13 (CC BY-SA 3.0) Outer membrane Cyt e ATP Synthase NADH NAD+H ATP Citric ADP acid cycle Matrix Suecinate Fumee Inner membrane Intermembrane space Mitochondrial electron transport chain by Fvasconcello (CCO) a. Analyze why…
In the 1930s, some physicians prescribed low doses of a compound called dinitrophenol (DNP) to help patients lose weight. This unsafe method was abandoned after some patients died. DNP uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to H+ . Explain how this could cause weight loss and death.
In the 1930s, some physicians prescribed low doses of a compound called dinitrophenol (DNP) to help patients lose weight. This unsafe method was abandoned after some patients died. DNP uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to H+. Chemical agents that cause this effect are called uncouplers. Explain how this could cause weight loss and also death. Considering the danger, is there any use for compounds like DNP or other uncouplers?
An important function of the inner mitochondrial membrane is to provide a selectively permeable barrier to the movement of water soluble molecules and thus to generate different chemical environments on either side of the mem- brane. However, many of the substrates and products of oxidative phosphorylation are water soluble and must cross the inner membrane. How does this transport occur?
When the antibiotic X is added to actively respiring mitochondria, several things happen: the yield of ATP decreases, the rate of O2 consumption increases, heat is released, and the pH gradient across the inner mitochondrial membrane increases. Does X act as an uncoupler or an inhibitor of oxidative phosphorylation? Explain the experimental observations in terms of the antibiotic’s ability to transfer K+ ions across the inner mitochondrial membrane.
Although the outer mitochondrial membrane is permeable to all small molecules, the inner mitochondrial membrane is essentially impermeable in the absence of specific transport proteins. Consider this information answer: The ATP generated by oxidative respiration is used throughout the cell. The majority of ATP production occurs in the mitochondrial matrix. How do you think ATP is made accessible to enzymes in the cytosol and other organelles?
The four complexes of the electron transport chain use the energy of electrons stored in reducing agents to create a concentration gradient of protons (H*) across the mitochondrial inner membrane. Give the number of protons pumped into the intermembrane space by each of the four complexes: complex I: complex II: complex III: complex IV:
Although the outer mitochondrial membrane is permeable to all small molecules, the inner mitochondrial membrane is essentially impermeable in the absence of specific transport proteins. Consider this information answer: Present two types of benefits derived from separating the reactions of glycolysis in the cytosol from those that occur during the citric acid cycle in the mitochondrion.
Under some conditions, mitochondrial ATP synthase has been observed to actually run in reverse. How would that situation affect the protonmotive force?
The glycerol-3-phosphate shuttle can transport cytosolic NADH equivalents into the mitochondrial matrix (see Fig. 15.11c). In this shuttle, the protons and electrons are donated to FAD, which is reduced to FADH₂. These protons and electrons are subsequently donated to coenzyme Q in the electron transport chain. End of Chapter Problem 86a How much ATP is generated per mole of glucose when the glycerol-3-phosphate shuttle is used? (Tolerance is +/- 2%) ATP are generated per glucose.
Although the outer mitochondrial membrane is permeable to all small molecules, the inner mitochondrial membrane is essentially impermeable in the absence of specific transport proteins. Consider this information answer: If the inner mitochondrial membrane were rendered as permeable as the outer membrane, how would that affect oxidative phosphorylation? Which specific processes would stop and which remain?
A central tenet in mitochondrial bioenergetics is that exergonic electron transfer drives the creation of an electrical potential () across the inner mitochondrial membrane (IMM). This is entirely true. Another tenet of mitochondrial bioenergetics, that you will read everywhere, is that this electrical potential is created by three proton pumps, Complexes I, III and IV. This is less true. A proton pump is this: It’s a protein that binds a proton from one side of a membrane, translocates that very proton across the membrane, through the protein, and ejects it into solution on the other side of the membrane. Complex I is a proton pump, but we did not discuss complex I. Complex III is NOT a proton pump, yet it creates electrical potential across the IMM. It is an electron/proton charge separation device. Complex IV is both types of these devices. Fifty percent of the electrical potential that complex IV creates is as a proton pump. But, 50% of the electrical potential that complex IV…