1. 1. Carbon fuels are oxidized in the citric acid cycle to yield electrons with high transfer potential. 2. This electron-motive force is converted into.

1. Carbon fuels are oxidized in the citric acid cycle to yield electrons with high transfer potential. 2. This electron-motive force is converted into a proton-motive force. 3. The proton-motive force is converted into phosphoryl transfer potential.

 Oxidation and ATP synthesis are coupled by transmembrane proton fluxes.

1. The intermembrane space between the outer and the inner membranes  Oxidative phosphorylation 2. The matrix which is bounded by the inner membrane:  most of the reactions of the citric acid cycle and fatty acid oxidation

1. Large multi subunit integral membrane protein complexes or coupling sites: couple electron transfer with H+ gradient generation › Complex I: NADH-Q oxidoreductase (MW =880 kd) Coupling Site 1 › Complex II: succinate-Q reductase complex (MW =140 kd) › Complex III: Q-cytochrome c oxido-reductase (MW = 250 kd). Coupling Site 2 › Complex IV: cytochrome c oxidase (MW = 160 kd) Coupling Site 3.

2. Small Mobile Electron Carriers: › Ubiquinone/Ubiquinol (Q/QH 2 ): small hydrophobic electron carriers which shuttle electrons between the large complexes and back and forth across the lipid bilayer. › Cytochrome c: is a small water soluble protein which is a mobile electron carrier and carries electrons between cytochrome bc1 complex and cytochrome c oxidase. 6

 Electron flow within these transmembrane complexes leads to the transport of protons across the inner mitochondrial membrane.  Electrons are carried from NADH-Q oxidoreductase to Q-cytochrome c oxidoreductase by the reduced form of coenzyme Q (Q).  Q also carries electrons from FADH2, generated in succinate dehydrogenase or (succinate-Q reductase) in the citric acid cycle, to Q-cytochrome c oxidoreductase  Cytochrome c, a small, soluble protein, shuttles electrons from Q-cytochrome c oxidoreductase to cytochrome c oxidase (complex IV), which catalyzes the reduction of O 2.  Succinate-Q reductase (Complex II), in contrast with the other complexes, does not pump protons. 8

 Q is a hydrophobic quinone that diffuses rapidly within the inner mitochondrial membrane.  Q is a quinone derivative with a long isoprenoid tail. › The number of five-carbon isoprene units in coenzyme Q depends on the species. › The most common form in mammals contains 10 isoprene units (coenzyme Q10).

The reduction of ubiquinone (Q) to ubiquinol (QH 2 ) proceeds through a semiquinone anion intermediate (Q. -). In the fully oxidized state (Q), coenzyme Q has two keto groups. The addition of one electron and one proton results in the semiquinone form (QH·). The semiquinone form is relatively easily deprotonated to form a semiquinone radical anion (Q·-). The addition of a second electron and proton generates ubiquinol (QH2), 10

 Thus, electron-transfer reactions of quinones are coupled to proton binding and release, a property that is key to transmembrane proton transport. 11

 Oxidation States of Flavins: › The reduction of flavin mononucleotide (FMN) to FMNH 2 proceeds through a semiquinone intermediate.

 Fe-S clusters in iron-sulfur proteins (nonheme iron proteins) play a critical role in a wide range of reduction reactions in biological systems.  Iron ions in these Fe-S complexes cycle between: › Fe 2+ (reduced state) › Fe 3+ (oxidized state)  Unlike quinones and flavins, iron-sulfur clusters generally undergo oxidation- reduction reactions without releasing or binding protons. 13

Several types of Fe-S clusters are known: A. A single iron ion bound by four cysteine residues. B. 2Fe-2S cluster with iron ions bridged by sulfide ions. C. 4Fe-4S cluster.  Each of these clusters can undergo oxidation-reduction reactions.

 NADH-Q oxidoreductase (also called NADH dehydrogenase): › an enormous enzyme (880 kd) › consists of at least 34 polypeptide chains. › consists of a membrane- spanning part and a long arm that extends into the matrix. › Contains FMN and Fe-S prosthetic groups.

 NADH is oxidized in the arm, and the electrons are transferred to reduce Q in the membrane.  The reaction catalyzed by this enzyme appears to be:

1. The initial step is the binding of NADH and the transfer of its two high-potential electrons to the flavin mononucleotide (FMN) prosthetic group of this complex to give the reduced form, FMNH2. NADH + H + NAD + FMN FMNH 2 Matrix Cytosol 17

2. Electrons are then transferred from FMNH2 to a series of three 4Fe4S, the second type of prosthetic group in NADH-Q oxidoreductase.  NADH-Q oxidoreductase contains: › 2Fe-2S cluster › 4Fe-4S cluster  Two protons move back to the matrix NADH + H + NAD + FMN FMNH 2 Fe 3+ Fe 2+ 2H + Matrix 18

3. Electrons in the 4Fe4S of NADH-Q oxidoreductase are shuttled to coenzyme Q.  Two hydrogen ions are pumped out of the matrix of the mitochondrion. NADH + H + NAD + FMN FMNH 2 Fe 3+ Fe 2+ UQ UQH 2 2H + Matrix Cytosol 19

4. The pair of electrons on bound QH2 are transferred to a 4Fe-4S center and the protons are released on the cytosolic side. 5. These electrons are transferred to a mobile Q in the hydrophobic core of the membrane, resulting in the uptake of two additional protons from the matrix. NADH + H + NAD + FMN FMNH 2 Fe 3+ Fe 2+ UQ UQH 2 Fe 3+ Fe 2+ UQ UQH 2 2H + Matrix Cytosol

1. NADH binds to a site on the vertical arm and transfers its electrons to FMN. 2. These electrons flow within the vertical unit to three 4Fe-4S centers. 3. Then they flow to a bound Q. The reduction of Q to QH 2 results in the uptake of two protons from the matrix.  4 Protons are pumped this way which is still under investigation

 It is an integral membrane protein of the inner mitochondrial membrane.  Contains three different kinds of Fe-S clusters: 1. 2Fe-2S 2. 3Fe-3S 3. 4Fe-4S. 22

 FADH 2 is generated in the citric acid cycle by the enzyme succinate dehydrogenase, with the oxidation of succinate to fumarate. 23

 Two electrons are transferred from FADH 2 directly to Fe-S clusters of succinate dehydrogenase.  The electrons are then passed to (Q) for entry into the electron-transport chain.  FADH 2 is generated by other reactions (such as: Glycerol phosphate dehydrogenase and fatty acyl CoA dehydrogenase).  This FADH 2 also transfers its electrons to (Q), to form (QH 2 ). 24

 The succinate-Q reductase complex and other enzymes that transfer electrons from FADH 2 to Q, in contrast with NADH-Q oxidoreductase, do not transport protons.  Consequently, less ATP is formed from the oxidation of FADH 2 than from NADH.

 The second of the three proton pumps in the respiratory chain (also known as cytochrome reductase).  The function of Q-cytochrome c oxidoreductase is to catalyze the transfer of electrons from QH 2 to oxidized cytochrome c (cyt c), a water-soluble protein, and concomitantly pump protons out of the mitochondrial matrix. 26

This enzyme is a homodimer with 11 distinct polypeptide chains. The major prosthetic groups, three hemes and a 2Fe-2S cluster, mediate the electron-transfer reactions between quinones in the membrane and cytochrome c in the intermembrane space.

 Q-cytochrome c oxidoreductase contains: › Cytochrome b562 › Cytochrome b566 › Cytochrome c1 › An iron sulfur protein › At least six other subunits.  A cytochrome is an electron-transferring protein that contains a heme prosthetic group.  The iron ion of a cytochrome alternates between a reduced ferrous (+2) state and an oxidized ferric (+3) state during electron transport. 28

 The enzyme contains three heme prosthetic groups contained within two cytochrome subunits: › Two b-type hemes within cytochrome b:  Heme b L (L for low affinity)  Heme b H (H for high affinity) › One c-type heme within cytochrome c1 (Heme c 1 ).  Hemes in the 3 classes of cytochrome ( a, b, c ) differ slightly in substituents on the porphyrin ring system.  Only heme c is covalently linked to the protein via thioether bonds to cysteine residues

 The enzyme also contains an iron-sulfur protein with an 2Fe-2S center (Rieske center).  This center is unusual in that one of the iron ions is coordinated by two his residues rather than two cysteine residues. › This coordination stabilizes the center in its reduced form, raising its reduction potential.  Finally, Q-cytochrome c oxidoreductase contains two distinct binding sites for ubiquinone termed (Q o ) and (Q i ), with the Qi site lying closer to the inside of the matrix. 30

 The mechanism for the coupling of electron transfer from Q to cytochrome c to transmembrane proton transport.  Facilitates the switch from the two- electron carrier ubiquinol to the one- electron carrier cytochrome c. 31

H+H+ H+H+ Q o site Cyt c Fe-S Cyt c 1 Cyt b L Cyt b H Q i siteQ  The first electron: 1.flows first to the Rieske 2Fe-2S cluster 2.then to cytochrome c1 3.finally to a molecule of oxidized cytochrome c, converting it into its reduced form.  The second electron: 1.transferred first to cytochrome b L 2.then to cytochrome b H 3.finally to an oxidized uniquinone bound in the Q i site.  This quinone (Q) molecule is reduced to a semiquinone anion (Q·-). QH2 QHQ Q.- 32

Fe-S Cyt c 1 Cyt b L Cyt b H Cyt c Q o site QH2 Q i site Q.- Q 33

H+H+ H+H+ H+H+ H+H+ Cyt c Fe-S Cyt c 1 Cyt b L Q o site Cyt b H QH2 Q i site Q.- QH2 Q 34

 It catalyzes the coupled oxidation of the reduced cyt c generated by Complex III, and reduction of O 2 to two molecules of H 2 O.  The four-electron reduction of oxygen directly to water without the release of intermediates is quite thermodynamically favorable.  G°´ = -231.8 kJ mol-1  As much of this free energy as possible must be captured in the form of a proton gradient for subsequent use in ATP synthesis. 36

 It consists of 13 subunits, 3 of which (subunits I, II, and III) are encoded by the mitochondrial genome.  Cytochrome c oxidase contains: › Three copper ions, arranged as two copper centers, designated A and B: 1. Cu A /Cu A : contains two copper ions linked by two bridging cysteine residues. This center initially accepts electrons from reduced cytochrome c. 2. Cu B : is coordinated by three histidine residues, one of which is modified by covalent linkage to a tyrosine residue. › Two heme A groups: 1. Heme a: functions to carry electrons from Cu A /Cu A 2. heme a 3 : passes electrons to Cu B, to which it is directly adjacent.  Together, heme a 3 and Cu B form the active center at which O 2 is reduced to H 2 O. 37

Cytochrome C Oxidase. The major prosthetic groups include: 1.Cu A /Cu A 2.heme a 3.heme a 3 -Cu B. Heme a 3 -Cu B is the site of the reduction of oxygen to water.. 38

Cyt c CuA/CuA Heme A Heme a3 Cu B Electrone transfer to Cu B FIRST ELECTRONE 39

Cyt c CuA/CuA Heme A Heme a3 Cu B OO OO Electrone transfer to Fe in Heme a 3 Both CuB and Fe in Heme a 3 are in reduced form Binding of O2 Formation of peroxide bridge SECOND ELECTRONE 40

Cyt c CuA/CuA Heme A Heme a3 Cu B OO H+H+ THIRD ELECTRONE Cleavage of O-O bond 41

Cyt c CuA/CuA Heme A Heme a3 Cu B OO H+H+ H+H+ FOURTH ELECTRONE Reduction of the Ferryl group 42

Cyt c CuA/CuA Heme A Heme a3 Cu B OO H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ Release of water 43

Cyt c CuA/CuA Heme A Heme a3 Cu B OO H+H+ H+H+ H+H+ H+H+ 44

 The four protons in this reaction come exclusively from the matrix.  Thus, the consumption of these four protons contributes directly to the proton gradient.  Each proton contributes (21.8 kJ mol-1) to the free energy associated with the proton gradient. 46

 Four "chemical" protons are taken up from the matrix side to reduce one molecule of O 2 to two molecules of H 2 O.  Four additional "pumped" protons are transported out of the matrix and released on the Cytosolic side in the course of the reaction.  The pumped protons double the efficiency of free-energy storage in the form of a proton gradient for this final step in the electron-transport chain.

 Still under study.  However, two effects contribute to the mechanism: 1. Charge neutrality tends to be maintained in the interior of proteins. › Thus, the addition of an electron to a site inside a protein tends to favor the binding of a proton to a nearby site. 2. Conformational changes take place, particularly around the heme a 3 -Cu B center, in the course of the reaction cycle. › These changes must be used to allow protons to enter the protein exclusively from the matrix side and to exit exclusively to the cytosolic side. 48

 Thus, the overall process catalyzed by cytochrome c oxidase is.  molecular oxygen is an ideal terminal electron acceptor, because its high affinity for electrons provides a large thermodynamic driving force. 49

 The reduction of O 2 is safe because:  Cytochrome c oxidase does not release partly reduced intermediates by holding O 2 tightly between Fe and Cu ions.  However, partial reduction generates small amounts of hazardous compounds (ROS). › Superoxide anion › peroxide. 50

 These TOXIC derivatives of molecular oxygen are scavenged by protective enzymes e.g. superoxide dismutase.  This enzyme catalyzes the conversion of two of the superoxide radicals into hydrogen peroxide and molecular oxygen.  The H 2 O 2 formed by superoxide dismutase and by other processes is scavenged by catalase, that catalyzes the dismutation of H 2 O 2 into H 2 O and O 2.

 So far, we have considered the flow of electrons from NADH to O 2, an exergonic process.  Next, we consider how this process is coupled to the synthesis of ATP, an endergonic process? 52

 The synthesis of ATP is carried out by A molecular assembly in the inner mitochondrial membrane called: › ATP synthase › mitochondrial ATPase › F 1 F 0 ATPase › Complex V 55

Chemiosmotic Hypothesis:  Complex I, Complex III and Complex IV pump protons across the inner mitochondrial membrane. › Pumping uses the energy liberated from the oxidation of NADH and FADH2 › Pumping generates a membrane potential because it generates an electrochemical gradient  Negative inside, positive outside  Alkaline inside, acidic outside 56

The difference in proton conc. (pH) and the electrical potential together represent a form of stored energy called (proton-motive force). This proton-motive force drives the synthesis of ATP by ATP synthase. 57

  G is given by: X+X+ X+X+ Outer sideInner side Conc. C1 Charge Z Conc. C2 ++++++ ------  V = potential across the membrane (V) 58

 Under typical mitochondrial conditions: › pH outside is 1.4 units lower than inside. (log 10 (c2/c1)) › The membrane potenial is 0.14V. (outside +ve) › Z=+1   G = 5.2 kcal mol -1 (21.8 kJ mol -1 ).  Thus, each proton that is transported out of the matrix to the cytosolic side corresponds to 5.2 kcal mol -1 of free energy. 59

 Testing the Chemiosmotic Hypothesis. ATP is synthesized when reconstituted membrane vesicles containing bacteriorhodopsin (a light- driven proton pump) and ATP synthase are illuminated.  The orientation of ATP synthase in this reconstituted membrane is the reverse of that in the mitochondrion

 The F 1 sector contains the catalytic sites of the synthase.  F 0 sector acts as a proton translocator.

 Consists of five types of polypeptide chains (  3,  3, , , and  ).  The  and  subunits, make up the bulk of the F 1, and are arranged alternately in a hexameric ring.  Both bind nucleotides but only the  subunits participate directly in catalysis.  The  subunit includes a long  - helical coil that extends into the center of the  3  3 hexamer.

  breaks the symmetry of the  3  3 hexamer: › each of the  subunits is distinct by virtue of its interaction with a different face of .  Distinguishing the three  subunits is crucial for the mechanism of ATP synthesis.

 Consists of a ring comprising from 10 to 15 c subunits that are embedded in the membrane.  A single a subunit binds to the outside of this ring.  The proton translocation depends on a subunit and the c ring.  The F 0 and F 1 sectors are connected in two ways: › by the internal  stalk. › by peripheral stalk.  The peripheral stalk consists of b 2 +  subunit.

1. A moving unit, or rotor, consisting of the c ring and the  stalk. 2. A stationary unit, or stator, composed of the remainder of the molecule.

 ATP synthesis mechanism:  The rate of incorporation of O 18 into Pi showed that about equal amounts of bound ATP and ADP are in equilibrium at the catalytic site, even in the absence of a proton gradient

 Changes in the properties of the three  subunits allow: 1. ADP and Pi binding 2. ATP synthesis 3. ATP release  The concepts of this initial proposal is refined by more recent crystallographic data: 67

 Interactions with the  subunit make the three  subunits inequivalent: 1. One  subunit can be in the T, or tight, conformation. › Binds ATP with great avidity. › Its affinity for ATP is so high that it will convert bound ADP and Pi into ATP with an equilibrium constant near 1, › The conformation of this subunit is sufficiently constrained that it cannot release ATP. 2. A second subunit will be in the L, or loose, conformation. › This conformation binds ADP and Pi. › It, too, is sufficiently constrained that it cannot release bound nucleotides. 3. The final subunit will be in the O, or open, conformation. › This form can exist with a bound nucleotide in a structure that is similar to those of the T and L forms, › But it can also convert to form a more open conformation and release a bound nucleotide. 68

 Suppose  subunit is rotated by 120 degree counterclockwise. 1. The T conformation will convert into O conformation:  ATP will be released 2. The L conformation will convert into T conformation:  The bound ADP+Pi will be converted into ATP. 3. The O conformation will convert into L conformation:  It will trap the bound ADP+Pi. So that it will not escape.

 A simple experimental system consisting of cloned      subunits only  The  were engineered to contain N-terminal polyhistidine tags,  The tags allowed the  3  3 assembly to be immobilized on a glass surface that had been coated with nickel ions.  The  subunit was linked to a fluorescently labeled actin filament  The addition of ATP caused the  to rotate in a counterclockwise direction, which could be seen directly under fluorescent microscope.

 When Asp 61 of C subunit is in contact with the hydrophobic part of the membrane, the residue must be in the neutral aspartic acid form, rather than in the charged, aspartate form.  Protons can pass into either of these channels, but they cannot move completely across the membrane.

 Suppose that the Asp 61 residues of the two c subunits that are in contact with a half- channel have given up their protons so that they are in the charged aspartate form.  The c ring cannot rotate in either direction, because such a rotation would move a charged aspartate residue into the hydrophobic part of the membrane.

 A proton can move through either half-channel to protonate one of the aspartate residues.  It is much more likely to pass through the channel that is connected to the cytosolic side of the membrane.  The entry of protons into the cytosolic half-channel is further facilitated by the membrane potential of +0.14 V (positive on the cytoplasmic side)

 If the aspartate residue is protonated to its neutral form, the c ring can now rotate, but only in a clockwise direction. › The newly protonated aspartic acid residue becomes in contact with the membrane. › The charged aspartate residue moves from contact with the matrix half- channel to the cytosolic half-channel › A different protonated aspartic acid residue moves from contact with the membrane to the matrix half-channel.

 The proton can then dissociate from aspartic acid and move through the half-channel into the proton-poor matrix to restore the initial state.

 The difference in proton concentration and potential on the two sides of the membrane leads to different probabilities of protonation through the two half-channels, which yields directional rotational motion.

 Recall that the number of c subunits in the c ring appears to range between 10 and 15.  Each 360-degree rotation of the  subunit leads to the synthesis and release of three molecules of ATP (1/120 o ).  Thus, if there are 10 c subunits in the ring (as was observed in a crystal structure of yeast mitochondrial ATP synthase), each ATP generated requires the transport of 10/3 = 3.33 protons. If there are 12 c ring, then 12/3 = 4 H+  For simplicity, we will assume that 3 protons must flow into the matrix for each ATP formed, but we must keep in mind that the true value may differ. 79

 NAD+ must be regenerated for glycolysis to continue.  How is cytosolic NADH reoxidized under aerobic conditions?  The inner mitochondrial membrane is impermeable to NADH and NAD+.  Thus electrons from NADH, rather than NADH itself, are carried across the mitochondrial membrane. 80

 FADH 2 transfers its electrons to Q, which then enters the respiratory chain as QH 2.  1.5 rather than 2.5 ATP are formed (FAD is the elect. Acceptor)  The use of FAD enables electrons from cytosolic NADH to be transported into mitochondria.  The price of this transport is one molecule of ATP/2e -.  This glycerol 3-phosphate shuttle is especially prominent in muscle and enables it to sustain a very high rate of oxidative phosphorylation. 82

 In heart and liver

 This shuttle, in contrast with the glycerol 3- phosphate shuttle, is readily reversible.  Consequently, NADH can be brought into mitochondria by the malate- aspartate shuttle only if the NADH/NAD+ ratio is higher in the cytosol than in the mitochondrial matrix.  This versatile shuttle also facilitates the exchange of key intermediates between mitochondria and the cytosol. 84

 Also called adenine nucleotide translocase or ANT  The highly charged ATP and ADP do not diffuse freely across the inner mitochondrial membrane.  The in and out flows of ATP and ADP are coupled by the translocase, which acts as an antiporter.

 The translocase, contains a single nucleotide-binding site that alternately faces the matrix and cytosolic sides of the membrane

 ATP and ADP (both devoid of Mg 2+ ) are bound with nearly the same affinity.  In actively respiring mitochondrion the membrane potential is positive.  The rate of binding-site eversion from the matrix to the cytosolic side is more rapid for ATP than for ADP because ATP has one more negative charge.  The membrane potential and hence the proton- motive force are decreased by the exchange of ATP for ADP, which results in a net transfer of one negative charge out of the matrix.  ATP-ADP exchange is energetically expensive; about a quarter of the energy yield from electron transfer by the respiratory chain is consumed to regenerate the membrane potential. 87

 Transporters (also called carriers) are transmembrane proteins that move ions and charged metabolites across the inner mitochondrial membrane.

 Many mitochondrial transporters consist of three similar 100-residue units. These proteins contain six putative membrane-spanning segments

 The best current estimates for the number of protons pumped out of the matrix per electron pair is: › 4 by NADH-Q oxidoreductase › 2 by Q-cytochrome c oxidoreductase › 4 by cytochrome c oxidase  Three protons are pumbed through the ATP synthase for each molecule of ATP.  One proton is consumed (neutralized) in transporting ATP from the matrix to the cytosol.  Hence, about 2.5 molecules of ATP are generated as a result of the flow of a pair of electrons from NADH to O 2. 90

 Electrons do not usually flow through the electron- transport chain to O 2 unless ADP is simultaneously phosphorylated to ATP.  Oxidative phosphorylation requires a supply of NADH (or FADH 2 ), O 2, ADP, and Pi.  The most important factor in determining the rate of oxidative phosphorylation is the level of ADP. 91

 The rate of oxygen consumption by mitochondria increases markedly when ADP is added and then returns to its initial value when the added ADP has been converted into ATP

 Specific inhibitors of electron transport were invaluable in revealing the sequence of electron carriers in the respiratory chain. 94

rotenone and amytal block electron transfer in NADH-Q oxidoreductase Antimycin A interferes with electron flow from cytochrome bH in Q- cytochrome c oxidoreductase cyanide (CN-), azide (N3-), and carbon monoxide (CO) block electron flow in cytochrome c oxidase Prevents utilization of electrons from NADH but not FADH 2 Prevents utilization of electrons from NADH and FADH 2 95

 Oligomycin and dicyclohexylcarbodiimide ( DCCD ) prevent the influx of protons through ATP synthase.  If actively respiring mitochondria are exposed to an inhibitor of ATP synthase, the electron-transport chain ceases to operate.  Indeed, this observation clearly illustrates that electron transport and ATP synthesis are normally tightly coupled.

 The coupling of electron transport and phosphorylation in mitochondria can be disrupted (uncoupled) by 2,4-dinitrophenol and certain other acidic aromatic compounds.  These substances carry protons across the inner mitochondrial membrane.

 Uncoupling is a means of generating heat to maintain body temperature in hibernating animals, in some newborn animals (including human beings), and in mammals adapted to cold.  Brown adipose tissue, which is very rich in mitochondria is specialized for this process.  The inner mitochondrial membrane of these mitochondria contains a large amount of uncoupling protein (UCP). 98

 UCP-1 forms a pathway for the flow of protons from the cytosol to the matrix.  In essence, UCP-1 generates heat by short- circuiting the mitochondrial proton battery. UCP-2 & UCP-3 also have been identified and may have a role in energy homeostasis.  This dissipative proton pathway is activated by free fatty acids liberated from triacylglycerols in response to hormonal signals, such as  -adrenergic agonists

1. 1. Carbon fuels are oxidized in the citric acid cycle to yield electrons with high transfer potential. 2. This electron-motive force is converted into.

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1. 1. Carbon fuels are oxidized in the citric acid cycle to yield electrons with high transfer potential. 2. This electron-motive force is converted into.

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Presentation on theme: "1. 1. Carbon fuels are oxidized in the citric acid cycle to yield electrons with high transfer potential. 2. This electron-motive force is converted into."— Presentation transcript:

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