The Reserve At Conway Gonzales, La, Hispanic Inventors And What They Invented, High Fence Elk Hunts Idaho, Articles I

The NADH generated from glycolysis cannot easily enter mitochondria. O b) It can occur only in the mitochondrion. b) glycolysis, citric acid cycle, electron transport chain, pyruvate oxidation. Why is the role NAD+ plays so important in our ability to use the energy we take in? 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 . Cb6f drops the electron off at plastocyanin, which holds it until the next excitation process begins with absorption of another photon of light at 700 nm by PS I. The electrons have made their way from water to NADPH via carriers in the thylakoid membrane and their movement has released sufficient energy to make ATP. The two acetyl-carbon atoms will eventually be released on later turns of the cycle; in this way, all six carbon atoms from the original glucose molecule will be eventually released as carbon dioxide. The ultimate replacement source of electrons is water, but water must lose four electrons and PS II can only accept one at a time. The electron transport chain and ATP synthase are embedded in the inner mitochondrial membrane. The entirety of this process is called oxidative phosphorylation. In oxidative phosphorylation, the energy comes from electrons produced by oxidation of biological molecules. NAD+ is a, Posted 6 years ago. Direct link to Taesun Shim's post Yes. An acetyl group is transferred to conenzyme A, resulting in acetyl CoA. The third type of phosphorylation to make ATP is found only in cells that carry out photosynthesis. OpenStax is part of Rice University, which is a 501(c)(3) nonprofit. The chloroplasts membrane has a phospholipid inner membrane, a phospholipid outer membrane, and a region between them called the intermembrane space (Figure 5.61). Direct link to Ellie Bartle's post Substrate level is the 'd, Posted 5 years ago. What would happen to the cell's rate of glucose utilization? 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. Such a compound is often referred to as an electron acceptor. is the final electron acceptor of the electron transport chain. The thylakoid membrane does its magic using four major protein complexes. If the intermembrane space of the mitochondria was increased, I would think that respiration would be less efficient, because now the electrons have to cross a larger space and lose much more energy. At the same time, its also one of the most complicated. This step regenerates NAD+ and FAD (the oxidized carriers) for use in the citric acid cycle. The entire textbook is available for free from the authors at http://biochem.science.oregonstate.edu/content/biochemistry-free-and-easy. The Citric Acid Cycle In eukaryotic cells, the pyruvate molecules produced at the end of glycolysis are transported into mitochondria, which are sites of cellular respiration. Without enough ATP, cells cant carry out the reactions they need to function, and, after a long enough period of time, may even die. is 29 years old and a self-employed photographer. What would happen to the energy stored in the proton gradient if it weren't used to synthesize ATP or do other cellular work? Through oxygen and glucose, ATP is ultimately created through the phosphorylation of ADP. Brown algae and diatoms add fucoxanthin (a xanthophyll) and red algae add phycoerythrin to the mix. Be sure you understand that process and why it happens. Substrate level is the 'direct' formation of ATP in glycolysis and the Krebs cycle, basically any ATP not formed during the electron transport chain. Direct link to syedashobnam's post the empty state of FADH2 , Posted 4 years ago. Based on a lot of experimental work, it appears that four H. With this information, we can do a little inventory for the breakdown of one molecule of glucose: One number in this table is still not precise: the ATP yield from NADH made in glycolysis. The net inputs for citric acid cycle is Acetyl, COA, NADH, ADP. The ability of plants to switch between non-cyclic and cyclic photosystems allows them to make the proper ratio of ATP and NADPH they need for assimilation of carbon in the dark phase of photosynthesis. The output involved in glycolysis is four ATP, two NADH (nicotinamide adenine dinucleotide hydrogen) and two pyruvate molecules. L.B. Unlike glycolysis, the citric acid cycle is a closed loop: The last part of the pathway regenerates the compound used in the first step. NADH and FADH2 made in the citric acid cycle (in the mitochondrial matrix) deposit their electrons into the electron transport chain at complexes I and II, respectively. Direct link to tmytltr's post if glycolysis requires AT, Posted 4 years ago. L.B. 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. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. Two carbon dioxide molecules are released on each turn of the cycle; however, these do not contain the same carbon atoms contributed by the acetyl group on that turn of the pathway. You, like many other organisms, need oxygen to live. Which part of the body will most likely use the cellular respiration? Which statement correctly describes how this increased demand would lead to an increased rate of ATP production? The interior of a leaf, below the epidermis is made up of photosynthesis tissue called mesophyll, which can contain up to 800,000 chloroplasts per square millimeter. In acetyl CoA formation, the carbon-containing compound from glycolysis is oxidized to produce acetyl CoA. If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA. The high-energy electrons from NADH will be used later to generate ATP. Cellular locations of the four stages of cellular respiration The proton gradient generated by proton pumping during the electron transport chain is a stored form of energy. This might seem wasteful, but it's an important strategy for animals that need to keep warm. Carbon dioxide is released and NADH is made. Net Input: Acetyl CoA, NAD+, ADP Net Output: Coenzyme A, CO2, NADH, ATP Not Input or Output: Pyruvate, Glucose, O2 (In the citric acid cycle, the two carbons from the acetyl group of acetyl CoA are oxidized to two molecules of CO2, while several molecules of NAD+ are reduced to NADH and one molecule of FAD is reduced to FADH2. If you're seeing this message, it means we're having trouble loading external resources on our website. The process of generating more ATP via the phosphorylation of ADP is referred to oxidative phosphorylation since the energy of hydrogen oxygenation is used throughout the electron transport chain. Approximately how much more free energy is supplied to the electron transport chain by NADH than by FADH2? Explain why only small amounts of catalysts are needed to crack large amounts of petroleum. For instance, hibernating mammals (such as bears) have specialized cells known as brown fat cells. Electron transport and oxidative phosphorylation is the third and final step in aerobic cellular respiration. Image by Aleia Kim. Our mission is to improve educational access and learning for everyone. 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. Try watching the, Posted 7 years ago. PS II performs this duty best with light at a wavelength of 680 nm and it readily loses an electron to excitation when this occurs, leaving PS II with a positive charge. The educational preparation for this profession requires a college education, followed by medical school with a specialization in medical genetics. Overall, in living systems, these pathways of glucose catabolism extract about 34 percent of the energy contained in glucose. Oxidative phosphorylation is the process by which the synthesization of ATP takes place. Drag the labels from the left (which represent numbers of carbon atoms) onto the diagram to identify the number of carbon atoms in each intermediate in acetyl CoA formation and the citric acid cycle. d. NADH Want to cite, share, or modify this book? Oxi, Posted a year ago. The two photosystems performing all of this magic are protein complexes that are similar in structure and means of operation. 1999-2023, Rice University. Oxidative phosphorylation is made up of two closely connected components: the electron transport chain and chemiosmosis. As the electrons travel through the chain, they go from a higher to a lower energy level, moving from less electron-hungry to more electron-hungry molecules. Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. 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. ATP synthase makes ATP from the proton gradient created in this way. When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). 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. 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? Eventually, the electrons are passed to oxygen, which combines with protons to form water. If a compound is not involved in oxidative phosphorylation, drag it to the "not input or output" bin. Direct link to sophieciurlik's post When it states in "4. NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The new Campbell Biology textbook updated the ATP yield totals to be 26-28 (instead of 30-32). Function. Photosynthesis is responsible for most of the oxygen in the atmosphere and it supplies the organic materials and most of the energy used by life on Earth. In chloroplasts, the light reactions of photosynthesis involving electron transfer occur in the thylakoid membranes (Figure \(\PageIndex{6}\)). In the matrix, NADH and FADH2 deposit their electrons in the chain (at the first and second complexes of the chain, respectively). https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Book%3A_Anatomy_and_Physiology_(Boundless)/21%3A_Respiratory_System/21.9%3A_Gas_Exchange/21.9B%3A_Internal_Respiration. Drag each compound to the appropriate bin. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions. This photochemical energy is stored ultimately in carbohydrates which are made using ATP (from the energy harvesting), carbon dioxide and water. The electron transport chain is present in multiple copies in the inner mitochondrial membrane of eukaryotes and in the plasma membrane of prokaryotes. 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. You have just read about two pathways in glucose catabolismglycolysis and the citric acid cyclethat generate ATP. If oxygen is not present, this transfer does not occur. Hm. A cell stays small to allow easier transport of molecules and charged particles from organelles. The same pigments are used by green algae and land plants. if glycolysis requires ATP to start how did the first glycolysis in history happen? Oxygen continuously diffuses into plants for this purpose. Thus at the end of GLYCOLYSIS, one glucose mocule has generated 2 pyruvate molecules (to the LINK REACTION) 2 ATP molecules (2 input, 4 output) 2 red NAD molecules (to OXIDATIVE PHOSPHORYLATION) NO CO 2 is produced by glycolysis The LINK REACTION Overview What are the electron carriers in oxidative phosphorylation? What affect would cyanide have on ATP synthesis? Oxidative phosphorylation marks the terminal point of the cellular respiration and the main sequence that accounts for the high ATP yield of aerobic cellular respiration. Dinitrophenol (DNP) is a chemical that acts as an uncoupling agent, making the inner mitochondrial membrane leaky to protons. Adenosine 5'-triphosphate (ATP), the most abundant energy carrier molecule, has two high-energy phosphate . You must remeber that life on this planet has been evolving for billions of years, it is highly unlikely that the originating system resembles the current system. The energy of the electrons is harvested and used to generate an electrochemical gradient across the inner mitochondrial membrane. After oxidative phosphorylation, the ATP created is in the mitochondrial matrix, right? Six-carbon glucose is converted into two pyruvates (three carbons each). (Figure 4.14). What Are the net inputs and net outputs of oxidative phosphorylation? I mean in glycolysis, one glucose is oxidised into two pyruvic acid and two NADHs. Separate biochemical reactions involving the assimilation of carbon dioxide to make glucose are referred to as the Calvin cycle, also sometimes referred to as the dark reactions. Acetyl CoA and Oxaloacetic Acid combine to form a six-carbon molecule called Citric Acid (Citrate). So. That's my guess and it would probably be wrong. One ATP (or an equivalent) is also made in each cycle. Electrons are donated to a carrier and ultimately are accepted by NADP+, to become NADPH. The excited electron from PS II must be passed to another carrier very quickly, lest it decay back to its original state. It consists of two stepsthe electron transport chain and chemiosmosis which create and use an electrochemical gradient to produce ATP from ADP. However, glycolysis doesn't require oxygen, and many anaerobic organismsorganisms that do . Direct link to Maulana Akmal's post how does the nadh from gl, Posted 7 years ago. Model-constructed genes affected the phosphorylation of mTOR and AKT in both Huh7 and Hep3B cells. 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. The protons flow back into the matrix through an enzyme called ATP synthase, making ATP. Source: BiochemFFA_5_3.pdf. This flow of hydrogen ions across the membrane through ATP synthase is called chemiosmosis. Direct link to Ivana - Science trainee's post The free energy from the , Posted 6 years ago. is a prosthetic group present in several components of the electron transport chain. Phosphorylation Definition. Fewer ATP molecules are generated when FAD+ acts as a carrier. Two net ATP are made in glycolysis, and another two ATP (or energetically equivalent GTP) are made in the citric acid cycle. Direct link to Ivana - Science trainee's post `C6H12O6 + 6O2 6CO2 + 6, Posted 5 years ago. Harvesting the energy of light begins in PS II with the absorption of a photon of light at a reaction center. When protons flow through ATP synthase, they cause it to turn (much as water turns a water wheel), and its motion catalyzes the conversion of ADP and Pi to ATP. Pyruvate oxidation. Base inputs and outputs on one glucose molecule. What are the inputs and outputs of pyruvate oxidation? if the volume of the intermembrane space was increased, what effect would this have on the function of a mitochondrion? . Pheophytin passes the electron on to protein-bound plastoquinones . After four electrons have been donated by the OEC to PS II, the OEC extracts four electrons from two water molecules, liberating oxygen and dumping four protons into the thylakoid space, thus contributing to the proton gradient. Cellular locations of the four stages of cellular respiration, 1. Other molecules that would otherwise be used to harvest energy in glycolysis or the citric acid cycle may be removed to form nucleic acids, amino acids, lipids, or other compounds. 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. Direct link to SanteeAlexander's post I thought it was 38 ATPs , Posted 6 years ago. Medical geneticists can be board certified by the American Board of Medical Genetics and go on to become associated with professional organizations devoted to the study of mitochondrial disease, such as the Mitochondrial Medicine Society and the Society for Inherited Metabolic Disease. Oxidative phosphorylation occurs in the mitochondria. These reactions take place in the cytosol. consent of Rice University. At this point, the light cycle is complete - water has been oxidized, ATP has been created, and NADPH has been made. Yes glycolysis requires energy to run the reaction. Where does it occur? Electrons from NADH and FADH2 are passed to protein complexes in the electron transport chain. This video explains what happens to pyruvate: In the brown fat cells, How many ATP do we get per glucose in cellular respiration? Chloroplasts are found in almost all aboveground plant cells, but are primarily concentrated in leaves. 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). Acetyl CoA and Oxalo, Posted 3 years ago. Energy for the entire process came from four photons of light. Oxidative phosphorylation" that the NADH and the FADH2 return to their "empty" forms NAD+ FADH2, the author meant FAD when referring to the "empty" forms, right? What are the inputs of oxidative phosphorylation? The oxygen liberated in the process is a necessary for respiration of all aerobic life forms on Earth. This. Cellular respiration is a metabolic pathway that breaks down glucose and produces ATP. In glycolysis, the carbon-containing compound that functions as the electron donor is __________. For example, sugars other than glucose are fed into the glycolytic pathway for energy extraction. Instead of electrons going through ferredoxin to form NADPH, they instead take a backwards path through the the proton-pumping b6f complex. What are the inputs and outputs of oxidative phosphorylation? Electron transport is a series of chemical reactions that resembles a bucket brigade in that electrons are passed rapidly from one component to the next, to the endpoint of the chain where oxygen is the final electron acceptor and water is produced. In poorly oxygenated tissue, glycolysis produces 2 ATP by shunting pyruvate away from mitochondria and through the lactate dehydrogenase reaction. Defend your response. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule. Direct link to richie56rich's post How much H2O is produced , Posted 4 years ago. As a result, the rate of cellular respiration, and thus ATP production, decreases. are not subject to the Creative Commons license and may not be reproduced without the prior and express written 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. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. Knockdown of ZCRB1 impaired the proliferation, invasion, migration, and colony formation in HCC cell lines. Does the glycolysis require energy to run the reaction? Indicate whether ATP is produced by substrate-level or oxidative phosphorylation (d-f). Complexes I, III, and IV use energy released as electrons move from a higher to a lower energy level to pump protons out of the matrix and into the intermembrane space, generating a proton gradient. View the full answer. Direct link to DonaShae's post Cellular Respiration happ, Posted 6 years ago. Where do the hydrogens go? (Note that not all of the inputs and outputs of oxidative phosphorylation are listed.) Direct link to Raya's post When the electron carrier, Posted 4 years ago. the source of the electrons H2O for photosynthesis versus NADH/FADH2 for oxidative phosphorylation, direction of proton pumping into the thylakoid space of the chloroplasts versus outside the matrix of the mitochondrion, movement of protons during ATP synthesis out of the thylakoid space in photosynthesis versus into the mitochondrial matrix in oxidative phosphorylation. 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 . -An enzyme is required in order for the reaction to occur Some cells of your body have a shuttle system that delivers electrons to the transport chain via FADH. mitochondrial matrix. We recommend using a Citric acid cycle. Thus, electrons are picked up on the inside of the mitochondria by either NAD+ or FAD+. Accessibility StatementFor more information contact us [email protected] check out our status page at https://status.libretexts.org. Oxidative phosphorylation is made up of two closely connected components: the electron transport chain and chemiosmosis. In this activity, you will identify the compounds that couple the stages of cellular respiration. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. 4 CO2, 2 ATP, 6 NADH + H+, 2 FADH2. Carbon atoms in acetyl CoA formation and the citric acid cycle How does oxidative phosphorylation occur? This flow of electrons allows the electron transport chain to pump protons to one side of the mitochondrial membrane. Figure \(\PageIndex{9}\) - Photosystem II of cyanobacteria. The input is NADH, FADH 2, O 2 and ADP. When protons flow back down their concentration gradient (from the intermembrane space to the matrix), their only route is through ATP synthase, an enzyme embedded in the inner mitochondrial membrane. In photosynthesis, water is the source of electrons and their final destination is NADP+ to make NADPH. 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. Cellular respiration and a cell's demand for ATP J.B. is 31 years old and a dispatcher with a local oil and gas company. Enter the email address you signed up with and we'll email you a reset link. What is the function? The electron transport chain would speed up, and the gradient would become stronger, The electron transport chain would stop, and the gradient would decrease, Both the electron transport chain and the gradient would stay the same, The electron transport chain would be re-routed through complex II, and the gradient would become weaker. Note that not all electron transport compounds in the electron transport chain are listed.a) FMN of Complex I -- Q -- Fe-S of Complex II -- FADH2 -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2b) FADH2 -- FMN of Complex I -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2c) O2 -- Cyt a of Complex IV -- Cyt c -- Fe-S of Complex III -- Q -- Fe-S of Complex II -- FMN of Complex I -- FADH2d) FADH2 -- FMN of Complex I -- Fe-S of Complex II -- Fe-S of Complex III -- Q -- Cyt a of Complex IV -- Cyt c -- O2, C) FADH2 -- FMN of Complex I -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2. Oxidative phosphorylation is the process by which ATP is synthesised when electrons are transported from the energy precursors produced in the citric acid cycle through various enzyme complexes to molecular oxygen. According to the amont of water molecules generated in chemiosmosis, all the hydrogen from the glucose should be used to form water, so do protons go into the mitochondria or mitochondria has extra protons itself? From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis. If there were no oxygen present in the mitochondrion, the electrons could not be removed from the system, and the entire electron transport chain would back up and stop. Hydrogen ions diffuse through the inner membrane through an integral membrane protein called ATP synthase (Figure 4.15b). In the last stage of cellular respiration, oxidative phosphorylation, all of the reduced electron carriers produced in the previous stages are oxidized by oxygen via the electron transport chain. cytosol. In this article, we'll examine oxidative phosphorylation in depth, seeing how it provides most of the ready chemical energy (ATP) used by the cells in your body. Cellular locations of the four stages of cellular respiration Energy from the light is used to strip electrons away from electron donors (usually water) and leave a byproduct (oxygen, if water was used). What are the inputs and outputs of pyruvate oxidation? Direct link to Ivana - Science trainee's post Cellular respiration is o, Posted 6 years ago. The entirety of this process is called oxidative phosphorylation. Oxygen continuously diffuses into plants for this purpose. The movement of electrons through this scheme in plants requires energy from photons in two places to lift the energy of the electrons sufficiently. If you're seeing this message, it means we're having trouble loading external resources on our website. It takes two electrons, 1/2 O2, and 2 H+ to form one water molecule. The electrons flow through the electron transport chain, causing protons to be pumped from the matrix to the intermembrane space. Answer: Net inputs are : NADH, ADP, O2 Net outpus are : NAD+, ATP, water Explanation: These compounds are involved in cellular respiration- Coenzyme A ,NADH ,ADP ,Acetyl CoA ,CO ,Glucose ,O ,ATP ,Pyruvate and water. in nucleophilic acyl substitution reactions. In eukaryotic cells, pyruvate is imported into the mitochondrial matrix for pyruvate oxidation. Labels may be used once, more than once, or not at all. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation. These high-energy carriers will connect with the last portion of aerobic respiration to produce ATP molecules. Oxidative phosphorylation is a process involving a flow of electrons through the electron transport chain, a series of proteins and electron carriers within the mitochondrial membrane. NAD+ is used as the electron transporter in the liver and FAD+ in the brain, so ATP yield depends on the tissue being considered. How much H2O is produced is the electron transport chain? harvesting energy of the proton gradient by making ATP with the help of an ATP synthase. This set of reactions is also where oxygen is generated. Drag each compound to the appropriate bin. (a) The electron transport chain is a set of molecules that supports a series of oxidation-reduction reactions. 3. The eight steps of the cycle are a series of chemical reactions that produces two carbon dioxide molecules, one ATP molecule (or an equivalent), and reduced forms (NADH and FADH2) of NAD+ and FAD+, important coenzymes in the cell. A primary difference is the ultimate source of the energy for ATP synthesis. In bacteria, both glycolysis and the citric acid cycle happen in the cytosol, so no shuttle is needed and 5 ATP are produced. 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. The development of celluar respiration began as a simple inefficient system progressing to it's current incarnation. ________ donates electrons to the electron transport chain. Phosphorylation reactions involve the addition of a phosphate group to another molecule. 6. Along the way, some ATP is produced directly in the reactions that transform glucose.