I mean in glycolysis, one glucose is oxidised into two pyruvic acid and two NADHs. The potential energy of this gradient is used to generate ATP. Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. 4 CO2, 2 ATP, 6 NADH + H+, 2 FADH2. Remember that all aqueous solutions contain a small amount of hydronium (HO) and hydroxide (OH) due to autoionization. oxidative phosphorylation input. It says above that NADH can't't cross the mitochondrial membrane, so there is some sort of shuttle protein. has not been pregnant previously; J.B. says he has never gotten a girl pregnant "that he knows of. Ultimately produces ATP, the whole process of the oxidation of NADH to produce energy into oxygen and water Chemiosmosis, a part of oxidative phosphorylation, is an energy coupling mechanism that uses energy stored in the form of an H+ gradient across a membrane to drive cellular . It would be released as heat, and interestingly enough, some types of cells deliberately use the proton gradient for heat generation rather than ATP synthesis. Cellular respiration is a nexus for many different metabolic pathways in the cell, forming a. Cyanide acts as a poison because it inhibits complex IV, making it unable to transport electrons. [Click here for a diagram showing ATP production], http://www.dbriers.com/tutorials/2012/04/the-electron-transport-chain-simplified/. Citric acid cycle. to function as the final electron acceptor in the electron transport chain, The effects of anaerobic conditions is a multi-protein complex within the electron transport chain. The ultimate replacement source of electrons is water, but water must lose four electrons and PS II can only accept one at a time. We'll look more closely at both the electron transport chain and chemiosmosis in the sections below. Yes. Try watching the, Posted 7 years ago. However, most current sources estimate that the maximum ATP yield for a molecule of glucose is around 30-32 ATP, Where does the figure of 30-32 ATP come from? Direct link to timroth500's post You must remeber that lif, Posted 7 years ago. Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct. Pyruvate is converted into acetyl-CoA before entering the citric acid cycle. This is the primary step in cellular respiration. But have you ever wondered why thats the case, or what exactly your body does with all that oxygen? d. NADH -The enyzmes involved in ATP synthesis must be attached to a membrane to produce ATP. When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). the microbial world. Drag each compound to the appropriate bin. Most of the ATP produced by aerobic cellular respiration is made by oxidative phosphorylation.The energy of O 2 released is used to create a chemiosmotic potential by pumping protons across a membrane. Phosphorylation Definition. (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.). d) All of the above. are licensed under a, Citric Acid Cycle and Oxidative Phosphorylation, Comparing Prokaryotic and Eukaryotic Cells, The Light-Dependent Reactions of Photosynthesis, Biotechnology in Medicine and Agriculture, Diversity of Microbes, Fungi, and Protists, Waterford's Energy Flow through Ecosystems. Substrate level is the 'direct' formation of ATP in glycolysis and the Krebs cycle, basically any ATP not formed during the electron transport chain. The components NAD + and NADH are common in both the oxidative phosphorylation pathway and the TCA cycle, while FAD and FADH 2 is bound tightly to the enzyme SDH (Korla and Mitra, 2014).The reduced molecules NADH and FADH 2 serve as electron donors for . is 29 years old and a self-employed photographer. In the fourth protein complex, the electrons are accepted by oxygen, the terminal acceptor. The energy from this oxidation is stored in a form that is used by most other energy-requiring reactions in cells. This complex protein acts as a tiny generator, turned by the force of the hydrogen ions diffusing through it, down their electrochemical gradient from the intermembrane space, where there are many mutually repelling hydrogen ions to the matrix, where there are few. The new Campbell Biology textbook updated the ATP yield totals to be 26-28 (instead of 30-32). If NADH becomes NAD+, it releases H+ and if FADH2 becomes FAD and would release 2H+. There are four complexes composed of proteins, labeled I through IV in Figure 4.15c, and the aggregation of these four complexes, together with associated mobile, accessory electron carriers, is called the electron transport chain. In animals, oxygen enters the body through the respiratory system. The electron transport chain and the production of ATP through chemiosmosis are collectively called oxidative phosphorylation. When a compound donates (loses) electrons, that compound becomes ___________. The coupling works in both directions, as indicated by the arrows in the diagram below. For example, sugars other than glucose are fed into the glycolytic pathway for energy extraction. A) 2 C For the growing plant, the NADPH and ATP are used to capture carbon dioxide from the atmosphere and convert it (ultimately) into glucose and other important carbon compounds. Oxidative Phosphorylation: Oxidative phosphorylation is the final metabolic step of cellular respiration that is used to produce. OpenStax is part of Rice University, which is a 501(c)(3) nonprofit. Book: Biochemistry Free For All (Ahern, Rajagopal, and Tan), { "5.01:_Basics_of_Energy" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "5.03:_Energy_-_Photophosphorylation" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "5.2:_Electron_Transport_and_Oxidative_Phosphorylation" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "01:_In_The_Beginning" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "02:_Structure_and_Function" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "03:_Membranes" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "04:_Catalysis" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "05:_Energy" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "06:_Metabolism" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "07:_Information_Processing" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "08:_Basic_Techniques" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "09:_Chapter_10" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10:_Chapter_11" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "11:_Point_by_Point" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "zz:_Back_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic", "authorname:ahern2", "Photophosphorylation", "showtoc:no", "license:ccbyncsa" ], https://bio.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fbio.libretexts.org%2FBookshelves%2FBiochemistry%2FBook%253A_Biochemistry_Free_For_All_(Ahern_Rajagopal_and_Tan)%2F05%253A_Energy%2F5.03%253A_Energy_-_Photophosphorylation, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), 5.2: Electron Transport and Oxidative Phosphorylation, Kevin Ahern, Indira Rajagopal, & Taralyn Tan, Electron transport: chloroplasts vs mitochondria, http://biochem.science.oregonstate.edu/content/biochemistry-free-and-easy, status page at https://status.libretexts.org, a membrane associated electron transport chain. start text, N, A, D, end text, start superscript, plus, end superscript, start text, F, A, D, H, end text, start subscript, 2, end subscript, 2, e, start superscript, minus, end superscript, 2, start text, H, end text, start superscript, plus, end superscript, start text, H, end text, start superscript, plus, end superscript. If the compound is not involved in glycolysis, drag it to the "not input or output" bin. Label the arrows indicating electrons carried by NADH. Luckily, cellular respiration is not so scary once you get to know it. Photosynthesis is an energy capture process found in plants and other organisms to harvest light energy and convert it into chemical energy. The result of the reactions is the production of ATP from the energy of the electrons removed from hydrogen atoms. In poorly oxygenated tissue, glycolysis produces 2 ATP by shunting pyruvate away from mitochondria and through the lactate dehydrogenase reaction. As a result, the rate of cellular respiration, and thus ATP production, decreases. When it states in "4. Direct link to Dallas Huggins's post The new Campbell Biology , Posted 6 years ago. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation. If you are redistributing all or part of this book in a print format, These electrons come originally from glucose and are shuttled to the electron transport chain by electron carriers, To see how a glucose molecule is converted into carbon dioxide and how its energy is harvested as ATP and, Glycolysis can take place without oxygen in a process called, Each stage of cellular respiration is covered in more detail in other articles and videos on the site. Remains the same: proton pumping rate, electron transport rate, rate of oxygen uptake In the sequential reactions of acetyl CoA formation and the citric acid cycle, pyruvate (the output from glycolysis) is completely oxidized, and the electrons produced from this oxidation are passed on to two types of electron acceptors. Indeed, it is believed that essentially all of the oxygen in the atmosphere today is the result the splitting of water in photosynthesis over the many eons that the process has existed. What are the 3 requirements inputs for oxidative phosphorylation? Is this couple infertile? In the citric acid cycle (also known as the Krebs cycle), acetyl CoA is completely oxidized. The coupled stages of cellular respiration The resulting compound is called acetyl CoA. This, as noted previously, occurs in the Calvin Cycle (see HERE) in what is called the dark phase of the process. As electrons move down the chain, energy is released and used to pump protons out of the matrix and into the intermembrane space, forming a gradient. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions. The Describe the relationships of glycolysis, the citric acid cycle, and oxidative phosphorylation in terms of their inputs and outputs. For example, the number of hydrogen ions that the electron transport chain complexes can pump through the membrane varies between species. Direct link to Chaarvee Gulia's post I don't quite understand , Posted 5 years ago. -A bond must be broken between an organic molecule and phosphate before ATP can form. The protein complexes containing the light-absorbing pigments, known as photosystems, are located on the thylakoid membrane. Instead, it must hand its electrons off to a molecular shuttle system that delivers them, through a series of steps, to the electron transport chain. These reactions take place in specialized protein complexes located in the inner membrane of the mitochondria of eukaryotic organisms and on the inner part of the cell membrane of prokaryotic organisms. Indicate whether ATP is produced by substrate-level or oxidative phosphorylation (d-f). the empty state of FADH2 is FADH, after oxidation it loses 1 h+ ion and elctron. The levels of glycolysis, pyruvate metabolism, oxidative phosphorylation, amino acid metabolism and lipid metabolism remained low in E7, 25 which was different from progressive cancer, 22, 25, 41 indicating that intramucosal ESCC may not initiate a large-scale cell growth and proliferation or suffer from nutrient and oxygen deprivation. Brown algae and diatoms add fucoxanthin (a xanthophyll) and red algae add phycoerythrin to the mix. If so, how does it get out of the mitochondrion to go be used as energy? (Assume that gramicidin does not affect the production of NADH and FADH2 during the early stages of cellular respiration.) To log in and use all the features of Khan Academy, please enable JavaScript in your browser. start superscript, 2, comma, 3, comma, 4, end superscript. Jan 9, 2023 OpenStax. In the matrix, NADH and FADH2 deposit their electrons in the chain (at the first and second complexes of the chain, respectively). In the electron transport chain, electrons are passed from one molecule to another, and energy released in these electron transfers is used to form an electrochemical gradient. Glycolysis is an ancient metabolic pathway, meaning that it evolved long ago, and it is found in the great majority of organisms alive today ^ {2,3} 2,3. This might seem wasteful, but it's an important strategy for animals that need to keep warm. nature of the terminal electron acceptor NADP+ in photosynthesis versus O2 in oxidative phosphorylation. In the matrix, NADH deposits electrons at Complex I, turning into NAD+ and releasing a proton into the matrix. Oxidative phosphorylation is powered by the movement of electrons through the electron transport chain, a series of proteins embedded in the inner membrane of the mitochondrion. Eventually, the electrons are passed to oxygen, which combines with protons to form water. The output of the photophosphorylation part of photosynthesis (O2, NADPH, and ATP), of course, is not the end of the process of photosynthesis. This ratio turns out to be 3 ATPs to 2 NADPHs. Cellular Respiration happens in your cells and you entire body is made up of cells, it goes on all throughout your body including your lungs and brain. In the electron transport chain, the free energy from the series of reactions just described is used to pump hydrogen ions across the membrane. The high-energy electrons from NADH will be used later to generate ATP. Failure in oxidative phosphorylation causes the deregulation of ATP-synthase activities in mitochondria and contributes to the elevation of oxidative stress and cell . Use of the lower-output FADH 2 may be a way to protect against poisons or mutations that might damage NADH usage (an internal redundant system). (Note that not all of the inputs and outputs of oxidative phosphorylation are listed.) is a prosthetic group present in several components of the electron transport chain. (Note that not all of the inputs and outputs of oxidative phosphorylation are listed.) The electron transport chain (Figure 4.15a) is the last component of aerobic respiration and is the only part of metabolism that uses atmospheric oxygen. Direct link to tmytltr's post if glycolysis requires AT, Posted 4 years ago. Knockdown of ZCRB1 impaired the proliferation, invasion, migration, and colony formation in HCC cell lines. Direct link to bart0241's post Yes glycolysis requires e, Posted 3 years ago. The NADH and FADH_2 produced in other steps deposit their electrons in the electron transport chain in the inner mitochondrial membrane. In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. The input is NADH, FADH 2, O 2 and ADP. Anaerobic glycolysis serves as a means of energy production in cells that cannot produce adequate energy through oxidative phosphorylation. NADH -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV -- O2, Chapter 8 Dynamic Study Module: An Introducti, David N. Shier, Jackie L. Butler, Ricki Lewis, John David Jackson, Patricia Meglich, Robert Mathis, Sean Valentine, Jane B. Reece, Lisa A. Urry, Michael L. Cain, Peter V Minorsky, Robert B Jackson, Steven A. Wasserman. Some cells of your body have a shuttle system that delivers electrons to the transport chain via FADH. ________ donates electrons to the electron transport chain. The electron transport chain (Figure 4.19 a) is the last component of aerobic respiration and is the only part of metabolism that uses atmospheric oxygen. 2 ATPs are used up by glycolysis this then begins the oxidative process of glycolysis. This step regenerates NAD+ and FAD (the oxidized carriers) for use in the citric acid cycle. Drag each compound to the appropriate bin. In plants and algae, the pigments are held in a very organized fashion complexes called antenna proteins that help funnel energy, through resonance energy transfer, to the reaction center chlorophylls. Fewer ATP molecules are generated when FAD+ acts as a carrier. Describe the relationships of glycolysis, the citric acid cycle, and oxidative phosphorylation in terms of their inputs and outputs. If a compound is not involved in oxidative phosphorylation, drag it to the "not input or output" bin. Besides the path described above for movement of electrons through PS I, plants have an alternative route that electrons can take. Fermentation results in a net production of 2 ATP per glucose molecule. It would seem to be the equivalent of going to and from a particular place while always going downhill, since electrons will move according to potential. The first is known as PQA. The steps in the photosynthesis process varies slightly between organisms. Thus NADPH, ATP, and oxygen are the products of the first phase of photosynthesis called the light reactions. Phosphate located in the matrix is imported via the proton gradient, which is used to create more ATP. The oxygen liberated in the process is a necessary for respiration of all aerobic life forms on Earth. The thylakoid membrane corresponds to the inner membrane of the mitochondrion for transport of electrons and proton pumping (Figure \(\PageIndex{4}\)). These atoms were originally part of a glucose molecule. Other cells of your body have a shuttle system that delivers the electrons via NADH, resulting in the production of 5 ATP. Direct link to Peony's post well, seems like scientis, Posted 6 years ago. Creative Commons Attribution License In each transfer of an electron through the electron transport chain, the electron loses energy, but with some transfers, the energy is stored as potential energy by using it to pump hydrogen ions across the inner mitochondrial membrane into the intermembrane space, creating an electrochemical gradient. Oxidative phosphorylation is an important energy-conserving mechanism coupling mitochondrial electron transfer to ATP synthesis. -An enzyme is required in order for the reaction to occur Pyruvate: Pyruvate is a molecule obtained as the main end-product of glycolysis performed in the cellular respiration mechanism. How much H2O is produced is the electron transport chain? and her husband, J.B., come to the clinic, saying they want to become pregnant. TP synthesis in glycolysis: substrate-level phosphorylation In the absence of oxygen, electron transport stops. Cellular locations of the four stages of cellular respiration, 1. The steps above are carried out by a large enzyme complex called the pyruvate dehydrogenase complex, which consists of three interconnected enzymes and includes over 60 subunits. Anaerobic conditions and acetyl CoA formation Although necessary for multicellular life, in an ironic twist of fate aerobic cellular respiration is thought to also be responsible for the processes that end multicellular life. Identifying and treating mitochondrial disorders is a specialized medical field. If you look in different books, or ask different professors, you'll probably get slightly different answers. Where does it occur? Electron Transport and Oxidative Phosphorylation; . From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis. What does substrate level phosphorylation means? Direct link to Ellie Bartle's post Substrate level is the 'd, Posted 5 years ago. Dinitrophenol (DNP) is a chemical that acts as an uncoupling agent, making the inner mitochondrial membrane leaky to protons. The mammalian circadian system is a hierarchically organized system, which controls a 24-h periodicity in a wide variety of body and brain functions and physiological processes. well, seems like scientists have recently discovered that the old ATP yield is not quite accurate, and the most recent data shows that it should be around 26-28, I thought it was 38 ATPs from the previous videos. Symptoms of mitochondrial diseases can include muscle weakness, lack of coordination, stroke-like episodes, and loss of vision and hearing. In bacteria, both glycolysis and the citric acid cycle happen in the cytosol, so no shuttle is needed and 5 ATP are produced. These reactions take place in the cytosol. What is true of oxidative phosphorylation? Direct link to Richard Wu's post Well, I should think it i, Posted 4 years ago. Glucose catabolism connects with the pathways that build or break down all other biochemical compounds in cells, and the result is somewhat messier than the ideal situations described thus far. The development of celluar respiration began as a simple inefficient system progressing to it's current incarnation. Overview of the steps of cellular respiration. Is it lungs? Electrons are donated to a carrier and ultimately are accepted by NADP+, to become NADPH. What Are the net inputs and net outputs of oxidative phosphorylation? Instead, H. Overview diagram of oxidative phosphorylation. Think about whether any carbon compounds play a role in oxidative phosphorylation. In chloroplasts, the light reactions of photosynthesis involving electron transfer occur in the thylakoid membranes (Figure \(\PageIndex{6}\)). Meanwhile, the excited electron from PS I passes through an iron-sulfur protein, which gives the electron to ferredoxin (another iron sulfur protein). Citric Acid Cycle output. [(Cl3CCO)2O], [(CH3CO)2O]\left[ \left( \mathrm { CH } _ { 3 } \mathrm { CO } \right) _ { 2 } \mathrm { O } \right] Direct link to syedashobnam's post the empty state of FADH2 , Posted 4 years ago. 3 domains of life proposed by Carl Woese 1970s 1 bacteria 2 Archaea prokaryotes 3 eukarya protozoa algae fungi plants animals cells nutrients cell wall motility bacteria s yes common archaea single in organic protozoa sing yes common no usual algae both photo synth yes rare fungi yes rare organic helminths m no always 9th organic which organisms can be pathogens bacteria . Energy from glycolysis The electron transport chain about to start churning out ATP. Use this diagram to track the carbon-containing compounds that play a role in these two stages. If oxygen isnt there to accept electrons (for instance, because a person is not breathing in enough oxygen), the electron transport chain will stop running, and ATP will no longer be produced by chemiosmosis. In photosynthesis, the energy comes from the light of the sun. The educational preparation for this profession requires a college education, followed by medical school with a specialization in medical genetics. Part A - Glycolysis From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis. After oxidative phosphorylation, the ATP created is in the mitochondrial matrix, right? Part of this is considered an aerobic pathway (oxygen-requiring) because the NADH and FADH2 produced must transfer their electrons to the next pathway in the system, which will use oxygen. This is because glycolysis happens in the cytosol, and NADH can't cross the inner mitochondrial membrane to deliver its electrons to complex I. Oxidative phosphorylation is made up of two closely connected components: the electron transport chain and chemiosmosis. This system, called cyclic photophosphorylation (Figure \(\PageIndex{8}\)) which generates more ATP and no NADPH, is similar to a system found in green sulfur bacteria. What are the electron carriers in oxidative phosphorylation? GLYCOLYSIS location. The electrons from Complexes I and II are passed to the small mobile carrier Q. Q transports the electrons to Complex III, which then passes them to Cytochrome C. Cytochrome C passes the electrons to Complex IV, which then passes them to oxygen in the matrix, forming water. Or are the Hydrogen ions that just came back through the ATP synthase going to be used for forming H2O?? The electron transport chain forms a proton gradient across the inner mitochondrial membrane, which drives the synthesis of ATP via chemiosmosis. The similarities of photophosphorylation to oxidative phosphorylation include: In some ways, the movement of electrons in chloroplasts during photosynthesis is opposite that of electron transport in mitochondria. Overall, what does the electron transport chain do for the cell? The chloroplasts are where the energy of light is captured, electrons are stripped from water, oxygen is liberated, electron transport occurs, NADPH is formed, and ATP is generated. The roles of these complexes, respectively, are to capture light energy, create a proton gradient from electron movement, capture light energy (again), and use proton gradient energy from the overall process to synthesize ATP. Each turn of the cycle forms three high-energy NADH molecules and one high-energy FADH2 molecule. Protons flow down their concentration gradient into the matrix through the membrane protein ATP synthase, causing it to spin (like a water wheel) and catalyze conversion of ADP to ATP. Are the protons tansported into mitochondria matix and later pumped out by ETC or intermembrane space to form electrochemical gradient, or are they left in cytosol?