Chapter 9 – Cellular Respiration and FermentationI. Metabolism: Sum of all the chemical reactions in a cell. Pathways are similar in all organisms.i. Catabolism: degradative pathways, oxidative, extracts energy in the form of ATP  Exergonicii. Anabolism: biosynthesis, reductive, needs energy, ATP provides Energy and gets converted to ADP  EndergonicATP (Adenosine triphosphate) is the predominant supplier of metabolic energy.II. The Nature of Chemical Energy and Redox Reactionsa. The structure and function of ATPi. ATP has a lot potential energy. Its three phosphate groups contain 4 negative charges that repel one another but confined to a smaller space.ii. When ATP is hydrolyzed, the terminal phosphate is released in a highly exergonic reaction. iii. The energy released from the hydrolysis of ATP is used to make things happen in a cell.iv. The phosphate released from ATP is transferred to another molecule changing its conformation.  Phosphorylation is exergonic. Therefore, this phosphorylationcouples endergonic reactions to exergonic reactions.b. What is a redox reaction?i. Redox reactions drive the formation of ATP.ii. In a redox reaction, one compound looses electrons and another compound gains it. Electrons may be completely transferred or they may shift positions withina covalent bond.iii. The electron donor becomes oxidized, and the electron acceptor becomes reduced. Electron donors are always paired with electron acceptors.iv. The reduced compounds have a high potential energy and act as electron donors to a molecule that can receive that energy.v. The electron that is transferred is usually accompanied by a proton so that the reduced molecule gains a hydrogen atom.vi. The oxidation of Glucose (electron donor) releases energy  stored in the form of ATP. Oxygen (electron acceptor) gets reduced to water.C6H12O6 + 6 O2 ® 6 CO2 + 6 H2O + energyc. Cellular Respiration: OVERVIEWi. In cells, Glucose is oxidized through a series of controlled steps: Its energy is harnessed to fuel the synthesis of ATP.1. GLYCOLYSIS: one molecule of glucose  2 molecules of pyruvate. 2 net ATP are produced. 2NAD+  reduced to 2NADH.2. PYRUVATE PROCESSING: Pyruvate (3C)  Acetyl CoA(2C) + CO2 Another NADH is produced (per pyruvate molecule)3. CITRIC ACID CYCLE: Acetyl Co A gets oxidized to two CO2 molecules. Each cycle produces 3 NADH, 1 FADH2 and one ATP (by substrate level phosphorylation). 14. ELECTRON TRANSPORT AND CHEMIOSMOSIS: Electrons from NADH and FADH2 move through a series of proteins called electron transport chain. The potential energy released during these reactions is used to create a proton gradient which is used to drive the ATP production  oxidative PhoaphorylationIII. Glycolysis: Glucose  Pyruvatea. Glycolysis is a sequence of 10 enzymatic reaction  in the cytosoli. Initially energy input is needed to phosphorylate (energize) glucose.ii. 2 ATP molecules used in the investment phaseiii. Next set of reactions yields an energy payoff generating ATP and NADH.iv. ATP production here is called substrate level phosphorylation. Why?v. For each molecule of glucose processed, the net yields are 2 NADH, 2ATP and 2Pyruvate molecules.b. Regulation:i. High concentration of ATP regulate glycolysis by inhibiting one of the early enzymes (PFK= Enzyme 3) in the pathway Feed Back Inhibition. What is FBI? When an enzyme in a pathway is inhibited by the product of that pathway.ii. Regulation of the pathway by ATP allows the cell to conserve glucose (ex: store as glycogen or starch) when ATP is plentiful.IV. Pyruvate Processing: Pyruvate  Acetyl CoA, (under aerobic conditions)a. Pyruvate moves into mitochondrial matrix, reacts with coenzyme A to form Acetyl CoA. b. Pyruvate dehydrogenase complex catalyses this reaction. c. During this reaction NADH and CO2 produced (per pyruvate). V. The Citric Acid (Krebs) Cycle: Oxidizing Acetyl CoA    CO2a. 2C Acetyl CoA enters the cycle and combines with a 4C molecule to yield 6C, Citrate hence the name citric acid cycle.  in the mitochondrial matrixb. 8 Enzymatic reactions  each turn of the cycle produces 3NADH, 1FADH2, 1ATP and 2 CO2[oxidative steps are coupled with reduction of electron carriers].c. High level of ATP regulates some of the enzymes in the cycle. Regulation of both glycolysis and citric acid cycle allow cells to carefully match the rate at which they use glucose to their energy requirements.VI. WHAT happens to NADH and FADH2?a. For each molecule of glucose oxidized, 10 NADH, 2 FADH2, 4 ATP and 6 CO2 are produced.b. ATP is used to fuel endergonic reactions, and the CO2 is released (exhaled) as waste.c. The NADH and FADH2 are used to reduce oxygen to water. Oxidized NAD+ and FAD are recycled.  Most ATP are produced in this step. VII. Electron Transport and Chemiosmosis  Building a proton gradient to produce ATPa. Components of the electron transport chain (ETC):i. Four complexes of the ETC are proteins, anchored in the inner mitochondrial membrane. These contain chemical groups where oxidation reduction takes place.ii. Another component is a lipid-soluble coenzyme called Q that can move through the membrane shuttling electrons.iii. The electron carriers NADH and FADH2 donate electrons to the ETC. iv. ETC components are organized from least oxidized to most oxidized.2v. NADH donate electrons to complex I Q  complex III cyto c complex IV  O2vi. FADH2 donates electrons to II  Q  complex III cyto c  complex IV  O2vii. Oxygen is the final electron acceptor (therefore this is an aerobic oxidation of glucose) in many cell types, gets reduced to water  METABOLIC WATERb. The Chemiosmosis Hypothesis [explains how ATP is synthesized by a proton motive force]i. ETC uses the energy from the oxidation-reduction reactions to fuel the pumping of protons up the concentration gradient from the matrix to the inner mitochondrialmembrane space. [ inner membrane is virtually impermeable to hydrogen ions]ii. This creates a proton-motive force.iii. Another enzyme (ATP synthase enzyme) in the inner membrane then uses this electrochemical gradient to synthesize ATP. [The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria]iv. Experiments to support this hypothesis? Uncoupling agents? = DNP? Respiratoryinhibitors = CN- ?c. How is the ETC