Cellular respiration - Krebs Cycle

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    16-Apr-2017

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<ul><li><p>Cellular RespirationPart 2: Oxidative Decarboxylation, Krebs</p></li><li><p>Recall: LocationGlycolysis occurs in the cytoplasmKrebs cycle occurs in the matrixThe end product of glycolysis (pyruvate) must make its way into the mitochondria</p></li><li><p>Oxidative Decarboxylation</p></li><li><p>Pyruvate Oxidation / Oxidative DecarboxylationDecarboxylationRedox reactionCoenzyme A addition</p></li><li><p>Oxidative DecarboxylationPyruvate (3C) is converted into acetyl-CoA (2C) in order to be brought into the mitochondria</p></li><li><p>Oxidative DecarboxylationReaction type: decarboxylationredoxsynthesis</p><p>Enzyme: decarboxylasedehydrogenasesynthase</p><p>Energy: releasedFigure 9.10</p></li><li><p>Coenzyme ACoenzyme A is a large organic moleculeActive functional group is a thiolalso written as CoA-SH</p></li><li><p>Oxidative Decarboxylation Summary</p><p>2 pyruvate 2 acetyl-CoA</p><p>2 CO2 released</p><p>2 NADH produced</p></li><li><p>Krebs Cycle</p></li><li><p>Krebs CycleAlso known as the citric acid cycle (CAC) and the tricarboxylic acid cycle (TCA)</p><p>Krebs cycle is a cyclical process to:generate more high energy molecules (NADH, FADH2 and ATP)produce additional CO2 molecules (byproducts)</p></li><li><p>Citric Acid Cycle OverviewFor each turn of Krebs cycle:two carbons exit completely as CO2three NADH and one FADH2 are formedOne ATP is made by substrate-level phosphorylation</p><p>Figure 9.11</p></li><li><p>Krebs CycleFigure 9.12</p></li><li><p>Krebs Cycle: Step by StepStep 1:join 2 carbon molecule with a 4 carbon moleculeRecycling of CoA</p><p>reaction type: synthesis</p><p>enzyme: synthase</p><p>energy: absorbed</p></li><li><p>Krebs Cycle: Step by StepStep 2:rearrangement of atoms with the help of H2O</p><p>reaction type: isomerization</p><p>enzyme: isomerase</p><p>energy: equilibrium</p></li><li><p>Krebs Cycle: Step by StepStep 3:synthesis of CO2 and NADH6C 5C</p><p>reaction type: decarboxylationredoxenzyme: Decarboxylasedehydrogenaseenergy: released</p></li><li><p>Krebs Cycle: Step by StepStep 4:synthesis of CO2 and NADH5C 4CCoA returns</p><p>reaction type:decarboxylationredoxsynthesisenzyme: decarboxylasedehydrogenaseenergy: released</p></li><li><p>Krebs Cycle: Step by StepStep 5:ADP phosphorylation to ATPCoA recycled</p><p>Reaction type: substrate-level phosphorylationCleavageenzyme: kinaselyaseenergy: released</p></li><li><p>Krebs Cycle: Step by StepStep 6:FADH2 (energy molecule) formation</p><p>reaction type: redox</p><p>enzyme: dehydrogenase</p><p>energy: released</p></li><li><p>FAD / FADH2FAD flavin adenine dinucleotide (oxidized form)FADH2 flavin adenine dinucleotide (reduced form)Acts the same way as NAD+ NADH by accepting electrons</p></li><li><p>FAD / FADH2FAD flavin adenine dinucleotide (oxidized form)FADH2 flavin adenine dinucleotide (reduced form)Acts the same way as NAD+ NADH by accepting electrons</p></li><li><p>Krebs Cycle: Step by StepStep 7:rearranging the molecule for the next reaction</p><p>reaction type: hydration</p><p>enzyme: hydrase</p><p>energy: absorbed</p></li><li><p>Krebs Cycle: Step by StepStep 8:energy molecule formation &amp; recreating molecules for Krebs cycle</p><p>reaction type: redox</p><p>enzyme: dehydrogenase</p><p>energy: released</p></li><li><p>Krebs Cycle Summarytwo cycles of Krebs for EACH glucose molecule</p><p>acetyl-CoA oxaloacetate (per cycle)</p><p>2 CO2 released (per cycle)</p><p>3 NADH produced (per cycle)</p><p>1 FADH2 produced (per cycle)</p><p>1 ATP produced (per cycle)</p></li><li><p>Krebs Cycle</p></li></ul>

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