Rebecca Davenport 10 18 16 BIOL 1406 BW1 Ch 9 blueprint 1 Cellular Respiration the set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate ATP and then release waste products a Catabolic pathwaysi Release energy stored energy by breaking down complex molecules exergonic ii Energy produced is in the form of ATP and heat iii Carbs fats and proteins can all be consumed as fuel iv C6H12O6 6 O2 6 CO2 6 H2O Energy v Aerobic respiration consumes organic molecules and O2 and yields ATP 1 vi Anaerobic Respiration and Fermentation 1 Most cellular respiration requires O2 to produce ATP 2 Without O2 glycolysis couples with anaerobic respiration or fermentation to produce ATP 3 Anaerobic respiration is similar to aerobic respiration but consumes compounds other than O2 and uses an electron transport chain with a final electron acceptor other than O2 4 Fermentation a type of anaerobic respiration is a partial degradation of sugars that occurs without O2 and uses substrate level phosphorylation instead of an electron transport chain to generate ATP a Types of Fermentationi Fermentation consists of glycolysis plus reactions that regenerate NAD which can be reused by glycolysis ii Two common types are alcohol fermentation and lactic acid fermentation 1 Alcohol fermentation pyruvate is converted to ethanol in two steps 2 Lactic Acid Fermentation pyruvate is reduced by NADH forming lactate as an end product with no release of CO2 b Redox reactions the transfer of electrons during chemical reactions releases energy stored in organic molecules i ii Two types Oxidation and Reduction 1 Oxidation a substance loses electrons or is oxidized a Electron donor is called the reducing agent 2 Reduction a substance gains electrons or is reduced a Electron receptor is called the oxidizing agent iii During cellular respiration the fuel such as glucose is oxidized and O 2 is reduced c Stages of Cellular Respiration i Harvesting energy from glucose has three stages 1 Glycolysis sugar splitting breaks down glucose into 2 molecules of pyruvate a Occurs in cytoplasm b Two major phasesi Energy investment phase ii Energy payoff phase c Occurs whether or not O2 is present d Net yield 2ATP 2NADH e f In the presence of O2 pyruvate enters the mitochondrial matrix and is turned into Acetyl CoA i Yield 2CO2 2NADH 2 Citric Acid cycle a b Acetyl CoA enters the Citric Acid Cycle c Each turn of the Citric Acid Cycle yields i 2 CO2 1 ATP 3 NADH 1 FADH2 d Net Yield 4 CO2 2 ATP 6 NADH 2 FADH2 3 Oxidative and phosphorylation a OPP Electron transport chain chemiosmosis b c Electron transport Chain sequence of e carrier molecules that shuttle e down a series of redox reactions that release energy used to make ATP i Located in the inner mitochondrial membrane of mitochdrion ii NADH FADH2 harbor most of the energy iii Electron carriers alternate reduced and oxidized states iv Electrons drop in free energy as they go down the chain v Electrons are finally passed to O2 forming H2O d Chemiosmosis use energy stored in H gradient across a membrane to synthesize ATP i Electron transfer in the electron transport chain causes proteins to pump H across membrane ii H then moves back across the membrane passing through the protein complex ATP synthase iii ATP synthase uses the exergonic flow of H to drive phosphorylation of ATP 1 ATP Synthasea Synthesizes ATP form ADP Pi b Uses energy form existing H gradient iv The H gradient is referred to as a proton motive force 4 d Stepwise Energy harvest via Coenzymes i Glucose is broken down in a series of steps ii At key steps electrons are stripped from glucose in the form of a Hydrogen atom iii Electrons are usually first transferred to an electron acceptor NAD or FAD iv Each NADH FADH2 represents stored energy that can be used to synthesize ATP e Energy flow 1 During cellular respiration most energy flows in this sequence ii glucose NADH FADH2 electron transport chain proton motive force ATP f Regulation of Cellular Respiration via Feedback mechanisms i Feedback inhibition is the most common mechanism for metabolic control ii If ATP concentration begins to drop respiration speeds up when there is plenty of ATP respiration slows down iii Control of catabolism is based mainly on regulating the activity of enzymes at strategic points in the catabolic pathway
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