MCB 100 1st Edition Lecture 18Outline of Last Lecture I. What are some ways that a cell uses ATP? II. Respiration A. Glycolysis B. Krebs cycle C. Electron transport chain D. Oxidative phosphorylation Outline of Current Lecture I. Redox reactions II. Types of metabolism III. Metabolic pathways IV. GlycolysisV. The Kreb’s cycleVI. Electron transport chain Current LectureI. Chemoheterotrophic organisms make energy via Redox reactionsA. Redox reactions = oxidation - reduction reactions B. Redox reactions involve transfer of electrons from one atom to anotherC. Redox reactions don’t always require the involvement of oxygenD. Electrons are not destroyed in a redox reaction, just transferred from one type of atom to anotherE. When some compound gets oxidized (loss of electrons) some other compound has to be reduced (gain of electrons)F. Oxidation = loss of electrons G. Reduction = gain of electrons (charge of the molecule becomes less)H. In biochemistry, an oxidation usually involves adding oxygen or removing a pair of hydrogens from a compoundi. Oxidation is the addition of an oxygen or the removal of 2 hydrogensii. Reduction is the addition of 2 hydrogens of the removal of an oxygeniii. Sugars are exactly mid-way b/w being completely oxidized (CO2) or completely reduced (saturated alkane) B. Reduction is the addition of 2 hydrogen atoms or the removal of an oxygen atom from a compoundThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.C. The electron donor starts out as a reduced compound that gets oxidized during the course of the reaction. The electron donor is the reducing reagent. The electron acceptor starts out as an oxidized compound that gets reduced during the course of the reaction. The electron acceptor is also known as the oxidizing reagent. (oxygen isa good oxidizing reagent) II. Chemoheterotrophy (both energy and carbon is from organic compounds) A. Type of metabolism:i. Aerobic respiration (terminal electron acceptor = oxygen) ex. Oxidation of glucoseii. Anaerobic respiration (terminal electron acceptor = an oxidized mineral) ex. NO3- reduction iii. Fermentation (terminal electron acceptor = an organic compound) ex. Ethanol fermentationiv. (terminal electron acceptor is the oxidized compound that gets reduced in metabolic redox reactions) II. Complex metabolic pathways are for energy production in living cells A. A metabolic pathway = series of enzyme catalyzed reactions that achieves the breakdown or building up of a complex molecule in small steps B. Steps in the oxidation of glucose: glycolysis, Kreb's cycle, electron transport chain (oxidative phosphorylation) C. Redox reactions often release a lot of energy- this is good because living cells need energy, but if this energy is released in an uncontrolled fashion it could damage the cell D. Redox reactions in cells occur in a series of gentle steps that often involve moving electrons or protons across a membrane to produce a charge gradient IV. GlycolysisA. A series of 10 reactions that results in a glucose molecule being partially oxidized to form two molecules of pyruvateB. C6H12O6 (glucose) --> 2 C3H4O3 (2 pyruvate) C. For each glucose molecule converted to 2 molecules of pyruvate: i. 2 ATPs are required to start the processii. 4 ATPs are produced by substrate level phosphorylation (for a net profit of 2 ATPs/1 glucose)iii. Also, 2 molecules of NAD+ are reduced to NADH + H+ II. The Kreb's cycleA. 8 reactions that result in the oxidation of pyruvate to CO2 B. When 2 molecules of pyruvate are oxidized to 6 molecules of carbon dioxide: i. 8 molecules of NAD+ are reduced to NADH + H+ii. 2 molecules of FAD are reduced to FADH2 iii. 2 ATPs made by substrate level phosphorylation B. At the end of glycolysis and the Kreb's cycle the glucose has been oxidized to 6 molecules of CO2 and 10 molecules of NAD+ and 2 molecules of FAD have been reduced to NADH + H+ and FADH2 II. Electron transport chainA. Oxidative phosphorylation = series of redox reactions involving membrane bound enzymes and electron carriers that results in the re-oxidation of NADH + H+ back to NAD+, reduction of O2 to H2O and the production of ~34 ATPs per glucoseB.Oxidative phosphorylation yields a proton motive force (PMF) that is sufficient to produce ~3 ATPs per NADH oxidized and 2 ATPs per FADH2
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