Campbell Biology
12th Edition
ISBN: 9780135188743
Author: Urry
Publisher: PEARSON
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Chapter 9, Problem 14TYU
SCIENTIFIC INQUIRY 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.
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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?
The production of a hydrogen ion concentration gradient powers the production of ATP in both photosynthesis and cellular respiration. 2,4-Dinitrophenol (DNP) is an organic compound that 'undoes' the hydrogen ion concentration gradient without the production of ATP. It does this by increasing the membrane permeability to hydrogen ions. One use of DNP is as a herbicide.For a brief period in the 1930s, DNP was marketed as a diet pill. Because DNP prevents the production of ATP, the human body will begin to use alternate forms of energy. The result is an increase in the metabolism of fats in the body, thus reducing total body fat. In the presence of DNP, the energy that normally would be converted to ATP for use in the cells is converted to heat instead, causing dangerously high body temperatures.DNP is classified as an illegal substance in Canada and the U.S. although it is still marketed as a commercial chemical. In recent years, several deaths have been reported, primarily in the…
Figure 7.11 Dinitrophenol (DNP) is an "uncoupler"
that makes the inner mitochondrial membrane
"leaky" to protons. It was used until 1938 as a weight-
loss drug. What effect would you expect DNP to have
on the change in pH across the inner mitochondrial
membrane? Why do you think this might be an
effective weight-loss drug?
Intermembrane
space
Mitochondrial
matrix
ATP Synthase
ADP
Inner mitochondrial
membrane
ATP
Figure 7.11 ATP synthase is a complex, molecular machine that uses a proton (H) gradient to form ATP from
ADP and inorganic phosphate (Pi). (Credit: modification of work by Klaus Hoffmeier)
Chapter 9 Solutions
Campbell Biology
Ch. 9.1 - Compare and contrast aerobic and anaerobic...Ch. 9.1 - WHAT IF? If the following redox reaction...Ch. 9.2 - Prob. 1CCCh. 9.3 - Prob. 1CCCh. 9.3 - What process in your cells produce the CO2 that...Ch. 9.3 - Prob. 3CCCh. 9.4 - Prob. 1CCCh. 9.4 - WHAT IF? In the absence of O2 as in question 1,...Ch. 9.4 - MAKE CONNECTIONS Membranes must be fluid to...Ch. 9.5 - Consider the NADH formed during glycolysis. What...
Ch. 9.5 - WHAT IF? A glucose-fed yeast cell is moved from...Ch. 9.6 - MAKE CONNECTIONS Compare the structure of a fat...Ch. 9.6 - Prob. 2CCCh. 9.6 - Prob. 3CCCh. 9.6 - Prob. 4CCCh. 9 - Describe the difference between the two processes...Ch. 9 - Which reactions in glycolysis are the source of...Ch. 9 - What molecular products indicate the complete...Ch. 9 - Briefly explain the mechanism by which ATP...Ch. 9 - Prob. 9.5CRCh. 9 - Prob. 9.6CRCh. 9 - Level 1: Knowledge/Comprehension 1. The immediate...Ch. 9 - Prob. 2TYUCh. 9 - Prob. 3TYUCh. 9 - Prob. 4TYUCh. 9 - What is the oxidizing agent in the following...Ch. 9 - When electrons flow along the electron transport...Ch. 9 - Prob. 7TYUCh. 9 - Prob. 8TYUCh. 9 - Prob. 9TYUCh. 9 - Prob. 10TYUCh. 9 - INTERPRET THE DATA Phosphofructokinase is an...Ch. 9 - DRAW IT The graph here shows the pH difference...Ch. 9 - EVOLUTION CONNECTION AIP synthases are found in...Ch. 9 - SCIENTIFIC INQUIRY In the 1930s, some physicians...Ch. 9 - WRITE ABOUT A THEME: ORGANIZATION In a short essay...Ch. 9 - SYNTHESIZE YOUR KNOWLEDGE Coenzyme Q (CoQ) is sold...
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- Classify each of the following examples as: (1) potential energy, (2) kinetic energy, or (3) a transformation of energy DOD electron transport causes hydrogen ions (H+) to accumulate in a membrane-enclosed compartment sunlight heat ATP supplies one of its phosphates to a membrane protein, activating it so that it can transport a specific molecule glucose (a monosaccharide sugar with the chemical formula C6H1206) 1. potential energy 2. kinetic energy 3. energy transformationarrow_forwardHow much energy is required to pump a mole of protons in a mitochondria with the following conditions? pH of matrix = 8.2, pH of intermembrane space 7.4, membrane potential of - 65 mV (N-side relative to P-side), temperature = 37C. Express answer to the nearest 0.1 kJ/mole.arrow_forwardAlthough 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?arrow_forward
- Figure 7.11 Dinitrophenol (DNP) is an "uncoupler" that makes the inner mitochondrial membrane "leaky" to protons. It was used until 1938 as a weight-loss drug. What effect would you expect DNP to have on the change in pH across the inner mitochondrial membrane? Why do you think this might be an effective weight-loss drug?arrow_forwardFigure 4.15 Cyanide inhibits cytochrome c oxidase, a component of the electron transport chain. If cyanide poisoning occurs, would you expect the pH of the intermembrane space to increase or decrease? What affect would cyanide have on ATP synthesis? Figure 4.15 (a) The electron transport chain is a set of molecules that supports a series of oxidation-reduction reactions. (b) ATP synthase is a complex, molecular machine that uses an H+ gradient to regenerate ATP from ADP. (c) Chemiosmosis relies on the potential energy provided by the H+ gradient across the membrane.arrow_forwardThe fatty acid side chains of the phospholipids in the inner mitochondrial membrane exhibit a large proportion of multiple unsaturations. As a result, will the membrane be hydrophobic or hydrophilic? Also will it be more fluid or more rigid? How do these characteristics help explain the observation that the inner membrane is impermeable to ions such as Mg2+ and Cl–? Hint: what moves these ions through the membrane?arrow_forward
- A new weight loss drug, Super Fat Melter, is introduced on the market but then quickly recalled after a few patients die. As it turns out, the pill makes the lipid bilayer of the inner mitochondrial membrane leaky to H+. What impact does this have on ATP production? Explain, with reference to the type of phosphorylation affected.arrow_forwardWhich of the following statements concerning the complete oxidation of FADH2 in the electron transport chain is NOT true? a. In the final step, electrons from cytochrome c to O2 reducing it to H2O in complex IV, and four protons are transported from the intermembrane space to the matrix. b. In the first step, electrons from FADH2 are transferred in complex II to ubiquinone, which does not transport any proton across the inner mitochondrion membrane. c. In the second step, complex III transfers the electrons from ubiquinone to cytochrome c, and four protons are transported from the matrix to the intermembrane space. d. The complete oxidation of FADH2 causes transfer of 6 protons and yields two ATP.arrow_forwardYou are studying the process of oxidative phosphorylation in the lab. You isolate several mitochondria from cells and place them in a buffered solution with a low pH and observe that the mitochondria begin to synthesize ATP. Which of the following is the best explanation for this observation? F It increases the conc. of OH-, causing the mitochondria to pump H+ to the intermembrane space. It increases the diffusion of H+ from the mitochondrial matrix to the intermembrane space. It increases the diffusion of H+ from the intermembrane space to the matrix. It increases the conc. of OH- in the mitochondrial matrix.arrow_forward
- Models such as the one shown in the illustration below are often used to represent the electron transport chain. Explain why this model is well-suited to this concept. Explain why metabolic processes such as cellular respiration and photosynthesis require a multi-stage release of energy, rather than a one-step reactionarrow_forwardEnergy-consuming active transport is used to move protons in all of the following directions except: A. from the mitochondrial matrix, across the mitochondrial cristae, into the intermembrane space B. from the extracellular fluid, across the plasma membrane, into the Halobacterium halobium cytosol C. from the cytosol of plant cells, across the vacuolar membrane, into the central vacuole D. from the cytosol of skeletal muscle cells, across the plasma membrane, into the extracellular fluid E. from the chloroplast stroma, across the thylakoid membrane, into the thylakoid spacearrow_forwardChemistry Compare the net production of ATP from four molecules of glucose (4 x C6) with that from one molecule of n-Tetracosanoic acid (Lignoceric acid, C24) as a result of oxidative metabolism (show your work). As a storage molecule, which is more energy efficient and why?arrow_forward
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