Chapter9.pdf BIOLOGY 108 - 0001
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This 8 page Class Notes was uploaded by Koral Shah on Sunday September 27, 2015. The Class Notes belongs to BIOLOGY 108 - 0001 at University of Missouri - Kansas City taught by Marilyn Yoder in Fall 2015. Since its upload, it has received 44 views. For similar materials see General Biology I in Biology at University of Missouri - Kansas City.
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Date Created: 09/27/15
AP Biology 20122013 Unit 4 Chapter 9 Cellular Respiration and Fermentation 91 Catabolic Pathway Energy Light energy g quotquotquotquotquotquotquotquot ECO SYSTEM ll x co H 0 Organic 2 2 molecules 1 0392 CBIIuIar resplrailon K in mitochondria l l Autotrophs convert sunlight to energy photosynthesis Heterotrophs consume food and oxygen to convert to energy humans Catabolic Pathways metabolic pathways that release stored energy by breaking down complex molecules Fermentation catabolic pathway partial degradation of sugars and other organic fuels Without oxygen Aerobic Respiration most efficient catabolic pathway oxygen and organic fuel are consumed as reactants Organic Compounds Oxygen gt Carbon Dioxide Water Energy Anaerobic Respiration similar to aerobic but used by prokaryotes Without oxygen Cellular Respiration includes both aerobic and anaerobic processes food provides the fuel for respiration i degradation of sugar C6HlZO6 Glucose 602 gt 6COZ 6H20 Energy ATP Heat T exergonic process releases free energy can happen spontaneously relocation of electrons releases energy stored in organic molecules Redox Reactions tranfer of one or more electrons from one reactant to another Oxidation loss of electrons from one substance Reduction addition of electrons to another substance Reducing Agent electron donor Oxidizing Agent electron acceptor Each electron travels with a protein a hydrogen atom NAD coenzyme electron carrier that transfers hydrogen atom to oxygen switches between reduced NADH and oxidized NAD states The Process enzymes called dehydrogenases remove a pair of hydrogen atoms from the substrate glucose and delivers the 2 electrons and 1 proton to the coenzyme NAD making it NADH that39s where the H in NADH comes from becomes oxidized I loses electron Na Cl gt Na Cl I becomes reduced I gains electron L Lose E Electrons O Oxidized Says G Gains E Electrons R Reduced I Electron loses potential energy when shifting from less electronegative atoms to more electronegative atoms lost energy can be used to do work Electron Transport Chain breaks the fall of electrons to oxygen into energy releasing steps consists of many proteins built into membrane of mitochondria Electrons removed from glucose are at the top of the chain higher energy 02 captures electrons at the bottom of the chain forming water So basically glucose gt NADH gt electron transport chain gt oxygen Cellular Respiration Stages 1 Glycolysis 2 Pyruvate Oxidation and Citric Acid Cycle 3 Oxidative Phosphorylation electron transport and chemiosmosis Electrons transferred Electrons trans erre via NADH Electron Transport Chain and C39xidative Phosphorylation w 2 ATP 2 ATP 32 ATP substrate level substrate level DXidatiV I phosphorylation phosphor ylation PhDSPhDIYlatlo l Glycolysis breaks down glucose into two pyruvate molecules enters mitochondrion is oxidized Citric Acid Cycle breakdown of glucose to C02 is completed Oxidative Phosphorylation energy released at each step of electron chain is stored and the mitochondrion can use it to make ATP from ADP enzyme adds inorganic phosphate to ADP SubstrateLevel Phosphorylation mode of ATP synthesis that accounts for about 10 of ATP enzyme transfers phosphate group from a substrate to ADP this substrate generated as an intermediate in catabolism of glucose 92 Glycolysis NAD derived from vitamin Niacin great electron donor and acceptor very easily oxidized or reduced transports electrons well Takes 2H from glucose glucose becomes oxidized Enzyme takes 2 electrons and 1 proton from the H39s taken from glucose Creates NADH neutralized Glycolysis Glucose gt 2 Pyruvate Molecules 2 ATP Anaerobic No Oxygen Fermentation Aerobic With Oxygen Proceeds to Krebs Cycle I ll Ill Ii U one molecule a of glucose I l3939 W 4 energy W investment m j mm to be recouped l 3192 later mi STEPB ll l H I39ll l 151 fructose 16 bisphosphate cleavage of sixcarbon sugarto two 1 STEPS threecarbon two molecules of a a sugars glyceraldehyde KW a 3phosphate STEP 7 l STEPB 1 STEP 9 l e n ergy mm WHO I m generation 391 two molecules of pyruvate Figure 138 Essential Cell Biology 2e 2004 Garland Science Cells invest 2 ATP molecules Phosphate breaks off ATP and attaches to glucose Phosphofructokinase negative feedback enzyme attaches phosphate group to glucose when a WHOLE LOT of ATP is present it will bind to and inhibit this enzyme and cause glycolysis to be halted Fructose 16 Biphosphate what the glucose molecule changes into with the phosphate group intermediary step of glycolysis G3P Splits from 6Carbon Sugar to Two 3Carbon Sugars each having one phosphate group G3P inorganic phosphate group from cytoplasm T now there39s TWO phosphate groups on each G3P Creates 1 ATP per phosphate pulled 4 Total 2 ATP were invested 4 ATP now gt Net Gain of 2 ATP And now we have 4 ATP and 2 Pyruvate YAY GLYCOLYSIS 93 Citric Acid Cycle After glycolysis has occurred pyruvate enters a mitochondrion via active transport Acetyl CoA what pyruvate is converted to in the mitochondrion conversion is carried out in 3 steps 1 Pyruvate39s carboxyl group is removed and given off as C02 2 Remaining 2carbon fragment is oxidized forming acetate 3 CoA is attached via its sulfur atom to the acetate forming the Acetyl CoA The Citric Acid Cycle aka Krebs Cycle Main Goal generate electron carriers to take electrons to electron transport chain 1 Breaks down pyruvate into three CO2 molecules including the CO2 during pyruvate conversion to Acetyl CoA 2 Oxaloacetate intermediate molecule after CoA part of Acetyl CoA is released Acetyl joins Oxaloacetate to form Citrate 3 Citrate is then oxidized NAD gt NADH and releases C02 4 CoA is once again attached bringing a phosphate 5 Phosphate is immediately removed generating 1 ATP per pyruvate molecule Tsubstratelevel phosphorylation 6 Most energy is transferred to NAD and the coenzyme FAD 7 Reduced enzymes NADH and FADH2 shuttle their electrons to the electron transport chain NET RESULT 10 NADH 2 FADH2 AND 2 ATP YAY CITRIC ACID CYCLE 4 CO239s released in CAC 2 per pyruvate PROCESS CITRIC ACID CYCLE if f The two red carbons enter gtCOOquot the cycle via acetyl CoA I3H2 ltH2 S CoA H20 H0 39039 2 HC lt0039 02 All 8 reactions I co NADH of the Cltl lC EH2 Ho Cf acid cycle CH3 I 1 CS 60039 3 occur in Acetyl GOA Citrate quotquotquotquotquotquot lsocitrate Too the in each turn of NAD sz gg frznucirs39izie HS CoA the c cle the 30039 two bylue CH2 the crlstae 00 carbons are 00 I CH2 gcgizverted to coo 00quot aKetoglutarate C 32 Oxaloacetate NAD The CITRIC ACID 4 NADH HS COA runs twice for each NADH L NAD glucose precursor coo l 1 170039 Cle HO CH 00 In the next cycle I I this red carbon HS CoA S COA coo 231568 a blue 5 Succinyl 00A Malate v COO39 GTP coo l 7 l FAD CH2 1 OH I GDP ATP 20 H CH2 or CH 6 000 ADP J Each reactlon IS catalyzed coo I by a different enzyme Succmate Fumarate FADH2 2011 Pearson Educalion Inc 8 Steps of the Citric Acid Cyclebook 1 Acetyl CoA adds its 2carbon acetyl group to oxaloacetate producing citrate 2 Citrate is converted to its isomer isocitrate by removal of one water molecule and addition of another 3 Isocitrate is oxidized reducing NAD to NADH resulting compound loses a C02 molecule 4 Another C02 is lost resulting compound is oxidized reducing NAD to NADH Remaining molecule is attached to coenzyme A by an unstable bond 5 CoA is displaced by a phosphate group which is transferred to GDP forming GTP functioning like ATP can be used to generate ATP 6 Two hydrogens are transferred to FAD forming FADH2 and oxidizing succinate 7 Addition of water molecule rearranges bonds in substrate 8 Substrate is oxidized reducing NAD to NADH and regenerating oxaloacetate Make sense Most ATP produced by respiration results from oxidative phosphorylation Summed Up Glycolysis net gain of 2 ATP Citric Acid Cycle net gain of 2 ATP 94 Chemiosmosis Book Stuff Electron Transport Chain collection of molecules in the inner membrane of mitochondria made of protein complexes labeled I through IV prosthetic groups nonprotein components essential for catalystic function Along the chain electrons switch off between reduced and oxidized states Cytochromes electron carriers between ubiquinone and oxygen Chain does not directly make any ATP Electron Transport Chain breaks the fall of electrons from food to oxygen so that the large free energy drop is broken into small manageable steps ATP Synthase the enzyme that makes ATP from ADP and inorganic phosphate works like an ion pump in reverse uses existing energy of ion gradient to power ATP synthesis difference in concentration of H Chemiosmosis energy stored in the form of a hydrogen ion gradient across a membrane is used to drive cellular work ow of H across a membrane The Process proteins move into binding sites on the rotor of membrane spinning it to catalyze ATP production Electron transport chain establishes the H gradient exergonic ow of electrons from NADH and FADH2 to pump H across the membrane ProtonMotive Force H gradient that results from accepting and donating of H along electron transport chain this force drives H back across the membrane through channels H will move back and forth across the membrane Chemiosmosis Summed Up mechanism that uses stored energy in the form of an H gradient across a membrane to drive cellular work In Mitochondria energy for gradient formation comes from exergonic redox reaction In Mitochondria ATP synthesis is the work performed In Chloroplast light drives gradient formation Protein complex of electron carriers lly carrying electrons from food V V 0 Electron transport cham 9 Chemrosmosns j V Oxidative phosphorylation Copyrigh 2008 Pearson ECUCBIIOH ncu DJDIIShlllg as Pearson Bengamln Cmnnmgs Energy Flow glucose gt NADH gt electron transport chain gt protonmotive force gt ATP ATP yield varies slightly depending on energy used to transport ATP type of shuttle used to transport electrons protonmotive force powering the mitrochonrion39s uptake of pyruvate Electron Transport Chain Basics 1 U NADH and FADH2 from citric acid cycle are dropped off at the top of the chain FADH2 is dropped off at the SECOND protein complex These electrons COME WITH a proton H Ubiquinone is the magic school bus that shuttles NADH and FADH2 from protein to protein along the transport chain chain goes from low to high electronegative protein complexes Continue to be passed down the chain releasing a little ATP at a time Final Electron Acceptor Oxygen VERY electronegative Water byproduct Active transport pumps protons across the mitochondria inner membrane ATP Synthase specific channel allowing hydrogens back into the mitochonrial matrix works like a water wheel What is all this Oxidative Phosphorylation SUPER productive End Result 3 ATP per 1 NADH 30 ATP 2 ATP per 1 FADH2 4 ATP Glycolysis 2 ATP Citric Acid Cycle 2 ATP GRAND TOTAL 38 ATP YAY CELLULAR RESPIRATION 95 Anaerobic Respiration Anaerobic Respiration oxidation of organic fuel to generate ATP without oxygen using the electron transport chain takes place in prokaryotes that live in environments lacking oxygen Note glycolysis CAN take place with or without oxygen with oxygen will go onto Krebs cycle without is fermentation Fermentation oxidation of organic fuel to generate ATP without oxygen NOT using the electron transport chain Glycolysis reactions that regenerate NAD by transferring NADH to pyruvate NAD is the reused to oxidize sugar by glycolysis glycolysis generates a net two ATP Alcohol Fermentation pyruvate is converted to ethanol 1 Carbon dioxide is released from pyruvate converted to acetaldehyde 2 Acetaldehyde is reduced by NADH to ethanol 3 This regenerates NAD supply needed to continue glycolysis ex Yeast Ultimate Products 2 Ethanol C02 Lactic Acid Fermentation pyruvate is reduced directly by NADH to form lactate no release of CO2 NADH loses electron to pyruvate replenishing supply of NAD used to make cheese and yogurt when oxygen is scarce human muscle cells make ATP through lactic acid fermentation ex when humans work out really hard Fermentation Anaerobic and Aerobic Respiration all three use glycolysis to produce pyruvate with net production of 2 ATP though substrate level phosphorylation NAD is the oxidizing agent in all three paths The Difference Mechanisms used to oxidize NADH back to NAD Fermentation organic molecule is the final electron acceptor Cellular Respiration NADH are transferred to an electron transport chain Aerobic final electron acceptor oxygen Anaerobic final electron acceptor electronegative nonoxygen molecule Respiration yields WAY more ATP than Fermentation Obligate Anaerobes carry out only fermentation or anaerobic respiration Facultative Anaerobes can function off of just either fermentation or respiration ex Yeast must take in sugar much faster when fermenting than when respiring Pyruvate Fork In The Road once pyruvate is formed if oxygen is present it will carry on to the citric acid cycle if oxygen is not present pyruvate is used as final electron acceptor to recyle NAD Glucose Cytosol Pvnuwn39e 1 o 2 39 i 2 39 I Ethanol Acolyl CoA or heme Krebs 39 yquot 96 Beyond Glycolysis aid the Citric Acid Cycle How we get the glucose Proteins gt Amino Acids gt Amino Group NH3 Removed Carbohydrates gt Sugars Fats gt Glycerol and Fatty Acids great energy storage better than carbs Proteins Carbohydrates Fats Amino Sugars Glycerol Fatty acids acids GchousIs Glucose lGlycornIdchydoGjn N f Pynivntc i wquot icon 139 l Knsas H CYCLE f m mu W mam 00 Beta Oxidationzrbreaks fatty acids down to 2carbon fragments which enter the citric acid cycle as acetyl CoA NADH and FADH2 are generated gt electron transport chain gt MORE ATP Phosphofructokinase enzyme that attaches phosphate to glucose in glycolysis inhibited through negative feedback if there is a stockpile of ATP Allosteric Enzyme inhibited by end product ATP and stimulated by AMP derived from ADP
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