Rebecca Davenport10/18/16BIOL 1406- BW1Ch 9 blueprint1. 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 pathways-i. 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 ATP3. 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 Fermentation-i. Fermentation consists of glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysisii. Two common types are alcohol fermentation and lactic acid fermentation1. 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 CO2b. Redox reactions- the transfer of electrons during chemical reactions releases energy stored in organic molecules.i.ii. Two types: Oxidation and Reduction1. 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 O2 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 phases-i. Energy investment phaseii. Energy payoff phasec. Occurs whether or not O2 is present.d. Net yield- 2ATP + 2NADHe.f. In the presence of O2, pyruvate enters the mitochondrial matrix and is turned into Acetyl CoA.i. Yield: 2CO2 + 2NADH2. Citric Acid cycle-a.b. Acetyl CoA enters the Citric Acid Cyclec. Each turn of the Citric Acid Cycle yields: i. 2 CO2 + 1 ATP + 3 NADH + 1 FADH2d. Net Yield: 4 CO2 + 2 ATP + 6 NADH + 2 FADH23. Oxidative and phosphorylationa. OPP = Electron transport chain + chemiosmosisb.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 energyiii. 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 H2Od. 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 membraneii. 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 Synthase-a. Synthesizes ATP form ADP + Pib. Uses energy form existing H+ gradient.iv. The H+ gradient is referred to as a proton-motive force4.d. Stepwise Energy harvest via Coenzymes:i. Glucose is broken down in a series of stepsii. At key steps, electrons are stripped from glucose, in the form of a Hydrogen atomiii. Electrons are usually first transferred to an electron acceptor, NAD+ or FADiv. Each NADH/FADH2 represents stored energy that can be used to synthesize ATPe. Energy flow:1. During cellular respiration, most energy flows in this sequence: ii. glucose → NADH/FADH2 → electron transport chain → proton-motive force → ATPf. 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
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