BIOL 1st Edition Lecture 12 Outline of Last Lecture I Cellular Respiration II Redox Reactions III Overview of Respiration IV First Two Stages of Respiration Outline of Current Lecture I Krebs Cycle II Oxidative Phosphorylation III Summary of Cellular Respiration IV Fermentation Current Lecture I Krebs Cycle a Catabolic pathway b Occurs in matrix of mitochondria only in the presence of O2 c 2 carbon acetyl group is completely broken down and oxidized to give 2 CO 2 d Electrons are transferred to NAD and FAD to produce reduced coenzymes NADH and FADH2 e Overall process i Acetyl CoA 2 carbon Oxaloacetate 4 carbon citric acid 6 carbons II Oxidative Phosphorylation a Occurs on the inner mitochondrial membrane b Uses electrons that were transferred to NADH and FADH2 in stages 2 3 reduced coenzymes c Electrons carried by reduced coenzymes are dropped at the electron transport chain ETC i Electron transport chain series of electron carrier molecules located on inner mitochondrial membrane d Electrons from the reduced coenzymes NADH and FADH2 are passed along the chain and eventually to O2 final electron acceptor i O2 H2O ii oxidized reduced e During some electron transfers along the electron transport chain protons H are pumped from the matrix into the inner membrane space creating an H gradient proton gradient i Proton gradient potential energy proton motive force f Protons can re enter the matrix of the mitochondria down their electrochemical gradient using a special transport protein called ATP synthase i ATP synthase transport protein for protons but also an enzyme that catalyzes reaction 1 ATP Phosphate ATP g As protons pass through the ATP synthase energy of proton gradient is harnessed to drive the endergonic reaction h Chemiosmosis using energy of proton gradient to make ATP i For every NADH that drops electrons at the electron transport chain enough energy is captured to make 3 ATPS j Every FADH2 can be used to make 2 ATPS i FADH2 2ATP k Most of the ATP in the cell is produced by chemiosmosis l Other important aspect is that NAD and FAD oxidized coenzymes are regenerated when they drop off their electrons i Now able to act as ACTIVE coenzymes to accept more electrons and continue respiration m Overall i Reactants NADH reduced coenzyme FADH2 reduced coenzyme O2 ii Products NAD oxidized coenzyme FAD oxidized coenzyme H2O ATP III IV Summary Table of Cellular Respiration Process Where Glycolysis Cytoplasm What Goes In 1 Glucose Transition to Mitochondria Cytoplasm mitochondria 2 Pyruvates Krebs Cycle Matrix of mitochondria 2 Acetyl Groups Oxidative Phosphorylation Inner mitochondrial membrane NADH FADH2 O2 Products 2 Pyruvates 2 NADH 2 ATPs 2 Acetyl Groups 2 CO2 2 NADH 4 CO2 6 NADH 2 FADH2 2 ATPs NAD FAD H2O 32 ATPs Fermentation a Anaerobic catabolism of organic nutrients b Glycolysis one or 2 more chemical reactions to regenerate NAD oxidized form of coenzyme c Products i 2 ATPs ii 2 Pyruvates iii 2 NADH d In the absence of O2 can t run the electron transport chain need O2 as the final electron acceptor e Electrons from NADH are transferred back to pyruvate to make one of two products i Lactic acid ii Ethanol f No ATP is generated by transferring electrons to pyruvate but it regenerates NAD so that glycolysis can continue g Energy yield from fermentation 2 ATP glucose h Examples i Ethanol fermentation yeast makes beer ii Muscle cells not enough O2 lactic acid fermentation makes sore muscles