Cellular Respiration Harvesting Chemical Energy ATP.

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Cellular Respiration Harvesting Chemical Energy

Cellular RespirationHarvesting Chemical Energy

ATP

1

Whats thepoint?

The pointis to makeATP!ATP2Harvesting stored energyEnergy is stored in organic moleculescarbohydrates, fats, proteins Heterotrophs eat these organic molecules fooddigest organic molecules to getraw materials for synthesisfuels for energycontrolled release of energyburning fuels in a series of step-by-step enzyme-controlled reactions

3We eat to take in the fuels to make ATP which will then be used to help us build biomolecules and grow and move and live!

heterotrophs = fed by others vs.autotrophs = self-feedersHarvesting stored energyGlucose is the modelcatabolism of glucose to produce ATPC6H12O66O2ATP6H2O6CO2+++CO2 + H2O + heat

fuel(carbohydrates)combustion = making a lot of heat energy by burning fuels in one steprespiration = making ATP (& some heat)by burning fuels in many small stepsCO2 + H2O + ATP (+ heat)ATP

glucoseglucose + oxygen energy + water + carbondioxiderespirationO2O2

+ heatenzymesATP4Movement of hydrogen atoms from glucose to waterHow do we harvest energy from fuels?Digest large molecules into smaller onesbreak bonds & move electrons from one molecule to anotheras electrons move they carry energy with themthat energy is stored in another bond, released as heat or harvested to make ATPe-++e-+loses e-gains e-oxidizedreducedoxidationreductionredoxe-5 They are called oxidation reactions because it reflects the fact that in biological systems oxygen, which attracts electrons strongly, is the most common electron acceptor. Oxidation & reduction reactions always occur together therefore they are referred to as redox reactions.As electrons move from one atom to another they move farther away from the nucleus of the atom and therefore are at a higher potential energy state.The reduced form of a molecule has a higher level of energy than the oxidized form of a molecule. The ability to store energy in molecules by transferring electrons to them is called reducing power, and is a basic property of living systems.

How do we move electrons in biology?Moving electrons in living systemselectrons cannot move alone in cellselectrons move as part of H atommove H = move electronspe+H+H+loses e-gains e-oxidizedreducedoxidationreductionC6H12O66O26CO26H2OATP+++oxidationreductionHe-6Energy is transferred from one molecule to another via redox reactions.C6H12O6 has been oxidized fully == each of the carbons (C) has been cleaved off and all of the hydrogens (H) have been stripped off & transferred to oxygen (O) the most electronegative atom in living systems. This converts O2 into H2O as it is reduced.The reduced form of a molecule has a higher energy state than the oxidized form. The ability of organisms to store energy in molecules by transferring electrons to them is referred to as reducing power. The reduced form of a molecule in a biological system is the molecule which has gained a H atom, hence NAD+ NADH once reduced.soon we will meet the electron carriers NAD & FADH = when they are reduced they now have energy stored in them that can be used to do work.Coupling oxidation & reductionRedox reactions in respiration release energy as breakdown organic moleculesbreak C-C bondsstrip off electrons from C-H bonds by removing H atomsC6H12O6 CO2 = the fuel has been oxidizedelectrons attracted to more electronegative atomsin biology, the most electronegative atom? O2 H2O = oxygen has been reducedcouple redox reactions & use the released energy to synthesize ATPC6H12O66O26CO26H2OATP+++oxidationreductionO2 7O2 is 2 oxygen atoms both looking for electronsLIGHT FIRE ==> oxidationRELEASING ENERGYBut too fast for a biological system

Oxidation & reductionOxidationadding Oremoving H loss of electronsreleases energyexergonicReductionremoving Oadding H gain of electronsstores energyendergonicC6H12O66O26CO26H2OATP+++oxidationreduction8Moving electrons in respirationElectron carriers move electrons by shuttling H atoms aroundNAD+ NADH (reduced)FAD+2 FADH2 (reduced)+HreductionoxidationPOOOOPOOOOCCONH2N+Hadenineribose sugarphosphatesNAD+nicotinamideVitamin B3niacinPOOOOPOOOOCCONH2N+HNADHcarries electrons as a reduced moleculereducing power!

How efficient!Build once,use many waysH9Nicotinamide adenine dinucleotide (NAD) and its relative nicotinamide adenine dinucleotide phosphate (NADP) which you will meet in photosynthesis are two of the most important coenzymes in the cell. In cells, most oxidations are accomplished by the removal of hydrogen atoms. Both of these coenzymes play crucial roles in this. Nicotinamide is also known as Vitamin B3 is believed to cause improvements in energy production due to its role as a precursor of NAD (nicotinamide adenosine dinucleotide), an important molecule involved in energy metabolism. Increasing nicotinamide concentrations increase the available NAD molecules that can take part in energy metabolism, thus increasing the amount of energy available in the cell.Vitamin B3 can be found in various meats, peanuts, and sunflower seeds. Nicotinamide is the biologically active form of niacin (also known as nicotinic acid). FAD is built from riboflavin also known as Vitamin B2. Riboflavin is a water-soluble vitamin that is found naturally in organ meats (liver, kidney, and heart) and certain plants such as almonds, mushrooms, whole grain, soybeans, and green leafy vegetables. FAD is a coenzyme critical for the metabolism of carbohydrates, fats, and proteins into energy. Overview of cellular respiration4 metabolic stagesAnaerobic respiration1. Glycolysisrespiration without O2in cytosolAerobic respirationrespiration using O2in mitochondria2. Pyruvate oxidation3. Krebs cycle4. Electron transport chain

C6H12O66O2ATP6H2O6CO2+++(+ heat)102006-2007

Whats thepoint?

The pointis to makeATP!ATP11ATP synthase enzymeH+ flows through itconformational changesbond Pi to ADP to make ATPset up a H+ gradientallow the H+ to flow down concentration gradient through ATP synthaseADP + Pi ATP

H+H+H+H+H+H+H+H+H+ATPADPP+

But How is the proton (H+) gradient formed?And how do we do that?2006-2007

H+H+H+H+H+H+H+H+H+ATPGot to wait untilthe sequel!Got the Energy? Ask Questions!ADPP+132006-2007Cellular RespirationHarvesting Chemical Energy

ATP

142006-2007

Whats thepoint?

The pointis to makeATP!ATP15Harvesting stored energyEnergy is stored in organic moleculescarbohydrates, fats, proteins Heterotrophs eat these organic molecules fooddigest organic molecules to getraw materials for synthesisfuels for energycontrolled release of energyburning fuels in a series of step-by-step enzyme-controlled reactions

16We eat to take in the fuels to make ATP which will then be used to help us build biomolecules and grow and move and live!

heterotrophs = fed by others vs.autotrophs = self-feedersHarvesting stored energyGlucose is the modelcatabolism of glucose to produce ATPC6H12O66O2ATP6H2O6CO2+++CO2 + H2O + heat

fuel(carbohydrates)combustion = making a lot of heat energy by burning fuels in one steprespiration = making ATP (& some heat)by burning fuels in many small stepsCO2 + H2O + ATP (+ heat)ATP

glucoseglucose + oxygen energy + water + carbondioxiderespirationO2O2

+ heatenzymesATP17Movement of hydrogen atoms from glucose to waterHow do we harvest energy from fuels?Digest large molecules into smaller onesbreak bonds & move electrons from one molecule to anotheras electrons move they carry energy with themthat energy is stored in another bond, released as heat or harvested to make ATPe-++e-+loses e-gains e-oxidizedreducedoxidationreductionredoxe-18 They are called oxidation reactions because it reflects the fact that in biological systems oxygen, which attracts electrons strongly, is the most common electron acceptor. Oxidation & reduction reactions always occur together therefore they are referred to as redox reactions.As electrons move from one atom to another they move farther away from the nucleus of the atom and therefore are at a higher potential energy state.The reduced form of a molecule has a higher level of energy than the oxidized form of a molecule. The ability to store energy in molecules by transferring electrons to them is called reducing power, and is a basic property of living systems.

How do we move electrons in biology?Moving electrons in living systemselectrons cannot move alone in cellselectrons move as part of H atommove H = move electronspe+H+H+loses e-gains e-oxidizedreducedoxidationreductionC6H12O66O26CO26H2OATP+++oxidationreductionHe-19Energy is transferred from one molecule to another via redox reactions.C6H12O6 has been oxidized fully == each of the carbons (C) has been cleaved off and all of the hydrogens (H) have been stripped off & transferred to oxygen (O) the most electronegative atom in living systems. This converts O2 into H2O as it is reduced.The reduced form of a molecule has a higher energy state than the oxidized form. The ability of organisms to store energy in molecules by transferring electrons to them is referred to as reducing power. The reduced form of a molecule in a biological system is the molecule which has gained a H atom, hence NAD+ NADH once reduced.soon we will meet the electron carriers NAD & FADH = when they are reduced they now have energy stored in them that can be used to do work.Coupling oxidation & reductionRedox reactions in respiration release energy as breakdown organic moleculesbreak C-C bondsstrip off electrons from C-H bonds by removing H atomsC6H12O6 CO2 = the fuel has been oxidizedelectrons attracted to more electronegative atomsin biology, the most electronegative atom? O2 H2O = oxygen has been reducedcouple redox reactions & use the released energy to synthesize ATPC6H12O66O26CO26H2OATP+++oxidationreductionO2 20O2 is 2 oxygen atoms both looking for electronsLIGHT FIRE ==> oxidationRELEASING ENERGYBut too fast for a biological system

Oxidation & reductionOxidationadding Oremoving H loss of electronsreleases energyexergonicReductionremoving Oadding H gain of electronsstores energyendergonicC6H12O66O26CO26H2OATP+++oxidationreduction21Moving electrons in respirationElectron carriers move electrons by shuttling H atoms aroundNAD+ NADH (reduced)FAD+2 FADH2 (reduced)+HreductionoxidationPOOOOPOOOOCCONH2N+Hadenineribose sugarphosphatesNAD+nicotinamideVitamin B3niacinPOOOOPOOOOCCONH2N+HNADHcarries electrons as a reduced moleculereducing power!

How efficient!Build once,use many waysH22Nicotinamide adenine dinucleotide (NAD) and its relative nicotinamide adenine dinucleotide phosphate (NADP) which you will meet in photosynthesis are two of the most important coenzymes in the cell. In cells, most oxidations are accomplished by the removal of hydrogen atoms. Both of these coenzymes play crucial roles in this. Nicotinamide is also known as Vitamin B3 is believed to cause improvements in energy production due to its role as a precursor of NAD (nicotinamide adenosine dinucleotide), an important molecule involved in energy metabolism. Increasing nicotinamide concentrations increase the available NAD molecules that can take part in energy metabolism, thus increasing the amount of energy available in the cell.Vitamin B3 can be found in various meats, peanuts, and sunflower seeds. Nicotinamide is the biologically active form of niacin (also known as nicotinic acid). FAD is built from riboflavin also known as Vitamin B2. Riboflavin is a water-soluble vitamin that is found naturally in organ meats (liver, kidney, and heart) and certain plants such as almonds, mushrooms, whole grain, soybeans, and green leafy vegetables. FAD is a coenzyme critical for the metabolism of carbohydrates, fats, and proteins into energy. Overview of cellular respiration4 metabolic stagesAnaerobic respiration1. Glycolysisrespiration without O2in cytosolAerobic respirationrespiration using O2in mitochondria2. Pyruvate oxidation3. Krebs cycle4. Electron transport chain

C6H12O66O2ATP6H2O6CO2+++(+ heat)232006-2007

Whats thepoint?

The pointis to makeATP!ATP24ATP synthase enzymeH+ flows through itconformational changesbond Pi to ADP to make ATPset up a H+ gradientallow the H+ to flow down concentration gradient through ATP synthaseADP + Pi ATP

H+H+H+H+H+H+H+H+H+ATPADPP+

But How is the proton (H+) gradient formed?And how do we do that?2006-2007

H+H+H+H+H+H+H+H+H+ATPGot to wait untilthe sequel!Got the Energy? Ask Questions!ADPP+2610 reactionsconvert glucose (6C) to 2 pyruvate (3C) produces: 4 ATP & 2 NADHconsumes:2 ATPnet: 2 ATP & 2 NADHglucoseC-C-C-C-C-Cfructose-1,6bPP-C-C-C-C-C-C-PDHAPP-C-C-C G3PC-C-C-PpyruvateC-C-COverviewATP2ADP2

ATP4ADP4NAD+22

2Pi2Pi2H271st ATP used is like a match to light a fire initiation energy / activation energy.

Destabilizes glucose enough to split it in two2006-2007Cellular RespirationStage 2 & 3:Oxidation of PyruvateKrebs Cycle

28pyruvate CO2Glycolysis is only the startGlycolysis

Pyruvate has more energy to yield3 more C to strip off (to oxidize)if O2 is available, pyruvate enters mitochondriaenzymes of Krebs cycle complete the full oxidation of sugar to CO22x6C3Cglucose pyruvate3C1C29Cant stop at pyruvate == not enough energy producedPyruvate still has a lot of energy in it that has not been captured.It still has 3 carbons! There is still energy stored in those bonds.

Cellular respiration

30

intermembranespaceinnermembrane outermembrane matrixcristae

Mitochondria StructureDouble membrane energy harvesting organellesmooth outer membranehighly folded inner membranecristaeintermembrane spacefluid-filled space between membranesmatrixinner fluid-filled spaceDNA, ribosomesenzymesmitochondrialDNA

What cells would have a lot of mitochondria?31Mitochondria Function

What does this tell us about the evolution of eukaryotes?Endosymbiosis!Dividing mitochondriaWho else divides like that?Advantage of highly folded inner membrane?More surface area for membrane-bound enzymes & permeases

Membrane-bound proteinsEnzymes & permeases

Oooooh!Form fits function!32Almost all eukaryotic cells have mitochondriathere may be 1 very large mitochondrion or 100s to 1000s of individual mitochondrianumber of mitochondria is correlated with aerobic metabolic activitymore activity = more energy needed = more mitochondria

What cells would have a lot of mitochondria?Active cells: muscle cells nerve cellspyruvate acetyl CoA + CO2Oxidation of pyruvateNAD3C2C1C[2x]

Pyruvate enters mitochondria

3 step oxidation processreleases 1 CO2 (count the carbons!)reduces 2 NAD 2 NADH (moves e-)produces acetyl CoAAcetyl CoA enters Krebs cycleWheredoes theCO2 go?Exhale!33CO2 is fully oxidized carbon == cant get any more energy out itCH4 is a fully reduced carbon == good fuel!!!Pyruvate oxidized to Acetyl CoA

Yield = 2C sugar + NADH + CO2reductionoxidationCoenzyme APyruvateAcetyl CoAC-C-CC-CCO2NAD+

2 x []34Release CO2 because completely oxidizedalready released all energy it can release no longer valuable to cell.

Because whats the point?The Point is to make ATP!!!Krebs cycleaka Citric Acid Cyclein mitochondrial matrix8 step pathwayeach catalyzed by specific enzymestep-wise catabolism of 6C citrate moleculeEvolved later than glycolysisdoes that make evolutionary sense?bacteria 3.5 billion years ago (glycolysis)free O2 2.7 billion years ago (photosynthesis)eukaryotes 1.5 billion years ago (aerobic respiration = organelles mitochondria)

1937 | 1953Hans Krebs1900-1981354C6C4C4C4C2C6C5C4CCO2CO2citrateacetyl CoACount the carbons!3Cpyruvatex 2oxidationof sugarsThis happens twice for each glucose molecule36A 2 carbon sugar went into the Krebs cycle and was taken apart completely. Two CO2 molecules were produced from that 2 carbon sugar. Glucose has now been fully oxidized!

But wheres all the ATP??? 4C6C4C4C4C2C6C5C4CCO2CO2citrateacetyl CoACount the electron carriers!3Cpyruvatereductionof electroncarriersThis happens twice for each glucose moleculex2CO2NADH

NADH

NADH

NADH

FADH2

ATP37Everytime the carbons are oxidized, an NAD+ is being reduced.

But waitwheres all the ATP??

So we fully oxidized glucose C6H12O6CO2& ended up with 4 ATP!Whassup?

Whats the point? 38

Krebs cycle produces large quantities of electron carriersNADHFADH2go to Electron Transport ChainElectron Carriers = Hydrogen Carriers

Whats so important about electron carriers?

H+H+H+H+H+H+H+H+H+ATPADP+ Pi39Energy accounting of Krebs cycle Net gain=2 ATP =8 NADH + 2 FADH21 ADP1 ATPATP

2x4 NAD + 1 FAD4 NADH + 1 FADH2pyruvate CO23C3x1C

40

Value of Krebs cycle?If the yield is only 2 ATP then how was the Krebs cycle an adaptation?value of NADH & FADH2electron carriers & H carriersreduced molecules move electronsreduced molecules move H+ ionsto be used in the Electron Transport Chainlike $$in the bank

412006-2007

Whats thepoint?

The pointis to makeATP!ATP42

H+H+H+H+H+H+H+H+H+And how do we do that?ATPBut Have we done that yet?ADPP+Set up a H+ gradientallow H+ to flow through ATP synthasepowers bonding of Pi to ADP

ADP + Pi ATP

2006-2007

NO!The final chapter to my story is next!Any Questions?442006-2007Cellular RespirationStage 4: Electron Transport Chain

45Cellular respiration

462006-2007

Whats thepoint?

The pointis to makeATP!ATP47

ATP accounting so farGlycolysis 2 ATP Krebs cycle 2 ATP Life takes a lot of energy to run, need to extract more energy than 4 ATP!

Whats the point? A working muscle recycles over 10 million ATPs per secondTheres got to be a better way!

48There is a better way!Electron Transport Chain series of molecules built into inner mitochondrial membranealong cristaetransport proteins & enzymes transport of electrons down ETC linked to pumping of H+ to create H+ gradientyields ~34 ATP from 1 glucose!only in presence of O2 (aerobic respiration)O2

Thatsounds morelike it! 49Mitochondria

Double membraneouter membraneinner membranehighly folded cristaeenzymes & transport proteinsintermembrane space fluid-filled space between membranes

Oooooh!Form fits function!50Electron Transport Chain

Intermembrane spaceMitochondrial matrixQCNADH dehydrogenasecytochromebc complexcytochrome coxidase complexInnermitochondrialmembrane51

G3PGlycolysisKrebs cycle8 NADH2 FADH2Remember the Electron Carriers? 4 NADH

Time tobreak openthe bank!glucose52Electron Transport Chain

intermembranespacemitochondrialmatrixinnermitochondrialmembraneNAD+QCNADH H2OH+e 2H+ + O2 H+H+eFADH212NADH dehydrogenasecytochromebc complexcytochrome coxidase complexFADeHH e- + H+NADH NAD+ + HHpeBuilding proton gradient!What powers the proton (H+) pumps?53

H+H+H+H+H+H+H+H+H+ATP

NAD+QCNADH H2OH+e 2H+ + O2 H+H+eFADH212NADH dehydrogenasecytochrome bc complexcytochrome coxidase complexFADeStripping H from Electron CarriersNADH passes electrons to ETCH cleaved off NADH & FADH2electrons stripped from H atoms H+ (protons)electrons passed from one electron carrier to next in mitochondrial membrane (ETC)transport proteins in membrane pump H+ (protons) across inner membrane to intermembrane spaceADP+ Pi

TA-DA!!Moving electronsdo the work!54Oxidation refers to the loss of electrons to any electron acceptor, not just to oxygen. Uses exergonic flow of electrons through ETC to pump H+ across membrane.

But what pulls the electrons down the ETC?

electronsflow downhill to O2oxidative phosphorylationO255Pumping H+ across membrane what is energy to fuel that?Cant be ATP!that would cost you what you want to make! Its like cutting off your leg to buy a new pair of shoes. :-(Flow of electrons powers pumping of H+

O2 is 2 oxygen atoms both looking for electrons

Electrons flow downhillElectrons move in steps from carrier to carrier downhill to O2each carrier more electronegativecontrolled oxidationcontrolled release of energy

make ATPinstead offire!56Electrons move from molecule to molecule until they combine with O & H ions to form H2O

Its like pumping water behind a dam -- if released, it can do work

H+ADP + PiH+H+H+H+H+H+H+H+We did it!ATPSet up a H+ gradientAllow the protons to flow through ATP synthaseSynthesizes ATP

ADP + Pi ATP

Are wethere yet?proton-motive force57The diffusion of ions across a membranebuild up of proton gradient just so H+ could flow through ATP synthase enzyme to build ATP

ChemiosmosisChemiosmosis links the Electron Transport Chain to ATP synthesis

So thatsthe point!58Chemiosmosis is the diffusion of ions across a membrane. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane.

Hydrogen ions (protons) will diffuse from an area of high proton concentration to an area of lower proton concentration. Peter Mitchell proposed that an electrochemical concentration gradient of protons across a membrane could be harnessed to make ATP. He likened this process to osmosis, the diffusion of water across a membrane, which is why it is called chemiosmosis.Peter MitchellProposed chemiosmotic hypothesisrevolutionary idea at the time1961 | 19781920-1992

proton motive force59

H+H+O2+QC32ATP2Pyruvate fromcytoplasmElectrontransportsystemATPsynthaseH2OCO2KrebscycleIntermembranespaceInnermitochondrialmembrane1. Electrons are harvested and carried to the transport system.2. Electrons provide energy to pump protons across the membrane.3. Oxygen joins with protons to form water.2H+NADHNADHAcetyl-CoAFADH2ATP4. Protons diffuse back in down their concentration gradient, driving the synthesis of ATP.Mitochondrial matrix21H+H+O2H+e-e-e-e-60Cellular respiration

2 ATP~2 ATP2 ATP~34 ATP+++~40 ATP61Summary of cellular respirationWhere did the glucose come from?Where did the O2 come from?Where did the CO2 come from?Where did the CO2 go?Where did the H2O come from?Where did the ATP come from?What else is produced that is not listed in this equation?Why do we breathe?C6H12O66O26CO26H2O~40 ATP+++62Where did the glucose come from?from food eatenWhere did the O2 come from?breathed inWhere did the CO2 come from?oxidized carbons cleaved off of the sugarsWhere did the CO2 go?exhaledWhere did the H2O come from?from O2 after it accepts electrons in ETCWhere did the ATP come from?mostly from ETCWhat else is produced that is not listed in this equation?NAD, FAD, heat!ETC backs upnothing to pull electrons down chainNADH & FADH2 cant unload HATP production ceasescells run out of energyand you die!Taking it beyondWhat is the final electron acceptor in Electron Transport Chain?O2So what happens if O2 unavailable?

NAD+QCNADH H2OH+e 2H+ + O2 H+H+eFADH212NADH dehydrogenasecytochrome bc complexcytochrome coxidase complexFADe63What if you have a chemical that punches holes in the inner mitochondrial membrane?2006-2007

Whats thepoint?

The pointis to makeATP!ATP64

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