Cellular Respiration

Cellular RespirationCellular Respiration

What is Cellular Respiration?What is Cellular Respiration?

The process of converting food energy The process of converting food energy into ATP energyinto ATP energy

CC66HH1212OO66 + 6 O + 6 O22 → → 6 CO6 CO22 + 6 H + 6 H22O + 36 ATPO + 36 ATP

Why are both Photosynthesis and Cell Why are both Photosynthesis and Cell Respiration important to Ecosystems?Respiration important to Ecosystems?

Light is the ultimate Light is the ultimate source of energy for all source of energy for all ecosystemsecosystems Chemicals cycle and Chemicals cycle and Energy flowsEnergy flowsPhotosynthesis and Photosynthesis and cellular respiration are cellular respiration are opposite reactionsopposite reactions

Why do plants need both Why do plants need both chloroplasts and mitochondria?chloroplasts and mitochondria?

Chloroplasts use Chloroplasts use energy from the energy from the sun to make sun to make glucoseglucose

Mitochondria Mitochondria convert glucose to convert glucose to ATP—the energy ATP—the energy currency of the cellcurrency of the cell

Definitions: Oxidation-Definitions: Oxidation-Reduction Reduction =

transfer of electrons from electron donor to electron acceptor

Example: A:H + B = A + B:H donor acceptor electron donordonor (reducing agent,

reductant) is itself oxidized

electron acceptoracceptor (oxidizing agent, oxidant) is itself

reduced

-- both oxidation and reductionmust occur simultaneously --one compound donates electronsto (reduces) a second compound;

thesecond accepts electrons from (oxidizes) the first.

RedoxRedox/oxidation-reduction-- electrons always move from compounds with lower reduction potential to compounds with higher reduction potential ( more positive).

Biological redoxBiological redox = Two half-

reactions

A:H AA:H A Reductant Oxidant + e-

  B B:HB B:H Oxidant + e- Reductant

(acceptor) (donor)

Standard reduction potential, E° Standard reduction potential, E° -- measure of the tendency of

oxidant to gain electrons, to become reduced, a potential energy.

Biological redoxBiological redox = Two half-

reactions

A:H AA:H A Reductant Oxidant + e-

  B B:HB B:H Oxidant + e- Reductant

(acceptor) (donor)

Standard reduction potential, E° Standard reduction potential, E°

-- Reduction potential (also known as redox

potential, oxidation / reduction potential or ORP) is

a measure of the tendency of a chemical species to

acquire electrons and thereby be reduced.

B B:HB B:H Oxidant + e- Reductant

(acceptor) (donor)

Standard reduction potential, E° Standard reduction potential, E°

-- Reduction potential (also known as redox

potential, oxidation / reduction potential or ORP) is

a measure of the tendency of a chemical species to

acquire electrons and thereby be reduced.

***********************************************************

So, the more negative the reduction potential is, the easier a reductant can reduce an oxidant and

The more positive the reductive potential is, the easier an oxidant can oxidize a reductant

The difference in reduction potential must be important************************************************************

Reduction Potential Difference Reduction Potential Difference ==EºEº

Eº = E°(acceptor) - E (donor)

measured in volts. The more positive the reduction potential difference is, the easier the redox reaction Work can be derived from the transfer of electrons and the ETScan be used to synthesize ATP.

The reduction potential can be related to free energy change by: GºGº = -n = -nFFEºEº

where n = # electrons transferred = 1,2,3F = 96.5 kJ/volt, called the Faraday constant

*********************************************************************************

Table of Standard Reduction Table of Standard Reduction

PotentialsPotentials

Oxidant + e- reductant

-- e.g., Lehninger, 5th ed., p. 511

Note:oxidants can oxidize every compound with less positive voltage -- (below it in the Table)reductants can reduce every compound with a less negativevoltage -- (above it in the Table)*****************************************************************************************

-- Electrons can move through a chain of donors and acceptors

-- In the electron transport chain, electrons flow down a gradient.

-- Electrons move from a carrierwith low reduction potential (high tendency to donate electrons)toward carriers with higherreduction potential (high tendencyto accept electrons).

-- The overall voltage drop from NADH

E = -(-0.32 V)to O Eº = +0.82 V is Eº = 1.14 V

-- This corresponds to a large freeenergy change of G = - nFE = -220 kJ/mole (n

=2) 

-- Since ATP requires 30.5 kJ/moleto form from ADP, more thanenough energy is available to synthesize 3 ATPs from theoxidation of NADH.

What is ATP?What is ATP?Adenosine TriphosphateAdenosine Triphosphate– 5-Carbon sugar (Ribose)5-Carbon sugar (Ribose)– Nitrogenous base (Adenine)Nitrogenous base (Adenine)– 3 Phosphate groups3 Phosphate groups

Energy currency of the Energy currency of the cellcell

The chemical bonds that The chemical bonds that link the phosphate groups link the phosphate groups together are high energy together are high energy bondsbonds

When a phosphate group When a phosphate group is removed to form ADP is removed to form ADP and P, small packets of and P, small packets of energy are releasedenergy are released

How is ATP used?How is ATP used?As ATP is broken down, it As ATP is broken down, it gives off usable energy to gives off usable energy to power chemical work and power chemical work and gives off some nonusable gives off some nonusable energy as heat.energy as heat.

Synthesizing molecules for Synthesizing molecules for growth and reproductiongrowth and reproductionTransport work – active Transport work – active transport, endocytosis, and transport, endocytosis, and exocytosisexocytosisMechanical work – muscle Mechanical work – muscle contraction, cilia and flagella contraction, cilia and flagella movement, organelle movement, organelle movementmovement

Why use ATP energy and not Why use ATP energy and not energy from glucose?energy from glucose?

Breaking down glucose yields too much energy Breaking down glucose yields too much energy for cellular reactions and most of the energy for cellular reactions and most of the energy would be wasted as heat.would be wasted as heat.

1 Glucose = 686 kcal1 Glucose = 686 kcal1 ATP = 7.3 kcal1 ATP = 7.3 kcal1 Glucose 1 Glucose → → 36 ATP36 ATP

How efficient are cells at converting glucose into How efficient are cells at converting glucose into ATP?ATP?– 38% of the energy from glucose yields ATP, 38% of the energy from glucose yields ATP,

therefore 62% wasted as heat.therefore 62% wasted as heat.

Cellular Respiration is a Redox ReactionCellular Respiration is a Redox Reaction

CC66HH1212OO66 + 6 O + 6 O22 → 6 CO→ 6 CO22 + 6 H + 6 H22OO

OxidationOxidation is the loss of electrons or H is the loss of electrons or H++

ReductionReduction is the gain of electrons or H is the gain of electrons or H++

Glucose is oxidized when electrons and HGlucose is oxidized when electrons and H++ are passed are passed to coenzymes NADto coenzymes NAD++ and FAD before reducing or and FAD before reducing or passing them to oxygen.passing them to oxygen.Glucose is oxidized by a Glucose is oxidized by a series of smaller stepsseries of smaller steps so so that smaller packets of energy are released to make that smaller packets of energy are released to make ATP, rather than one large explosion of energy.ATP, rather than one large explosion of energy.

(Oxidation)

(Reduction)

Cell Respiration can be divided into 4 Parts:Cell Respiration can be divided into 4 Parts:

1) Glycolysis1) Glycolysis2) Oxidation of Pyruvate / Transition Reaction2) Oxidation of Pyruvate / Transition Reaction3) The Krebs Cycle3) The Krebs Cycle4) The Electron Transport Chain and 4) The Electron Transport Chain and Chemiosmotic PhosphorylationChemiosmotic Phosphorylation

Where do the 4 parts of Cellular Where do the 4 parts of Cellular Respiration take place?Respiration take place?

Glycolysis: Glycolysis: – CytosolCytosol

Oxidation of Oxidation of Pyruvate:Pyruvate:– MatrixMatrix

The Krebs Cycled:The Krebs Cycled:– MatrixMatrix

Electron Transport Electron Transport Chain and Chain and Cheimiosmotic Cheimiosmotic Phosphorylation:Phosphorylation:– CristaeCristae

Parts of the MitochondriaParts of the Mitochondria

Anaerobic Respiration (no oxygen required, cytoplasm)Anaerobic Respiration (no oxygen required, cytoplasm)

1. Glycolysis(substrate level)

Glucose 4 ATP (Net 2 ATP)2 ATP 2 NADH

2 Pyruvate

Aerobic Respiration (oxygen required, mitochondria)Aerobic Respiration (oxygen required, mitochondria)

2. OxidationofPyruvate

2 Pyruvate 2 CO2

2 NADH2 Acetyl CoA

3. Krebs Cycle(substrate level)

2 Acetyl CoA 4 CO2

2 ATP6 NADH2 FADH2

4. ElectronTransportChain

(chemiosmotic)

10 NADH 32 ATP2 FADH2 6 H2O6 O2

Total: 36 ATP produced

ATP is made in two ways:ATP is made in two ways:1) 1) Substrate Level Substrate Level

PhosphorylationPhosphorylation (glycolysis (glycolysis & Krebs cycle)& Krebs cycle)

2) 2) Chemiosmotic Chemiosmotic PhosphorylationPhosphorylation (electron (electron transport chain)transport chain)

Substrate-Level Substrate-Level Phosphorylation:Phosphorylation:Energy and phosphate are Energy and phosphate are transferred to ADP using an transferred to ADP using an enzyme, to form ATP. enzyme, to form ATP. Phosphate comes from one Phosphate comes from one of the intermediate of the intermediate molecules produced from molecules produced from the breakdown of glucose.the breakdown of glucose.

GlycolysisGlycolysis

Glucose (CGlucose (C66) is split to make ) is split to make 2 Pyruvates (C2 Pyruvates (C33))– 11stst: ATP energy used to phosphorylate : ATP energy used to phosphorylate

glucose (stored energy)glucose (stored energy)– 22ndnd: phosphorylated glucose broken : phosphorylated glucose broken

down into two Cdown into two C33 sugar phosphates sugar phosphates– 33rdrd: the sugar phosphates are oxidized : the sugar phosphates are oxidized

to yield electrons and Hto yield electrons and H++ ions which are ions which are donated to 2 NADdonated to 2 NAD++ → → 2 NADH (stored 2 NADH (stored electron and hydrogen for the Electron electron and hydrogen for the Electron Transport Chain)Transport Chain)

– 44thth: The energy from oxidation is used to : The energy from oxidation is used to make 4 ATP molecules (net 2 ATP)make 4 ATP molecules (net 2 ATP)

This is substrate level phosphorylation This is substrate level phosphorylation because an enzyme transfers because an enzyme transfers phosphate to ADP making ATPphosphate to ADP making ATP

Glycolysis produces very little ATP Glycolysis produces very little ATP energy, most energy is still stored in energy, most energy is still stored in Pyruvate molecules.Pyruvate molecules.

Glucose 2 Pyruvate2 ATP 4 ATP (Net 2 ATP)

2 NADH

Oxidation of Pyruvate /Transition ReactionOxidation of Pyruvate /Transition Reaction

When Oxygen is present, 2 Pyruvates go to the matrix where they are converted into 2 Acetyl CoA (C2).Multienzyme complex: – 1st: each Pyruvate releases

CO2 to form Acetate. – 2nd: Acetate is oxidized and

gives electrons and H+ ions to 2 NAD+ → 2 NADH.

– 3rd Acetate is combined with Coenzyme A to produce 2 Acetyl CoA molecules.

2 NADH’s carry electrons and hydrogens to the Electron Transport Chain.

2 Pyruvate 2 CO2

2 NADH2 Acetyl CoA

The Krebs Cycle / Citric Acid CycleThe Krebs Cycle / Citric Acid Cycle

8 Enzymatic Steps in Matrix of Mitochondria: Break down and Oxidize each Acetyl CoA (2-C’s) to release 2 CO2 and yield electrons and H+ ions to 3 NAD+ + 1 FAD → 3 NADH + FADH2. This yields energy to produce ATP by substrate level phosphorylation.

The first step of the Krebs cycle combines Oxaloacetate (4 C’s) with Acetyl CoA to form Citric Acid, then the remaining 7 steps ultimately recycle oxalacetate.

Two Turns of the Krebs Cycle are required to break down both Acetyl Coenzyme A molecules.

The Krebs cycle produces some chemical energy in the form of ATP but most of the chemical energy is in the form of NADH and FADH2 which then go on to the Electron Transport Chain.

2 Acetyl CoA 4 CO2

2 ATP6 NADH2 FADH2

The Electron Transport ChainThe Electron Transport Chain

NADH and FADHNADH and FADH22 produced produced earlier, go to the Electron earlier, go to the Electron Transport Chain.Transport Chain.NADH and FADHNADH and FADH22 release release electrons to carriers/proteins electrons to carriers/proteins embedded in the membrane embedded in the membrane of the cristae. As the of the cristae. As the electrons are transferred, Helectrons are transferred, H++ ions are pumped from the ions are pumped from the matrix to the intermembrane matrix to the intermembrane space up the concentration space up the concentration gradient. Electrons are gradient. Electrons are passed along a series of 9 passed along a series of 9 carriers until they are carriers until they are ultimately donated to an ultimately donated to an Oxygen molecule. Oxygen molecule. ½ O½ O22 + 2 electrons + 2 H + 2 electrons + 2 H++ (from NADH and FADH(from NADH and FADH22) ) → → HH22O. O.

10 NADH 32 ATP2 FADH2 H2OOxygen

http://vcell.ndsu.nodak.edu/animations/etc/movie.htm

Sequence of RespiratoryElectron Carriers

InhibitorsInhibitors in greenin green

In-depth Summary of the Site In-depth Summary of the Site ComponentsComponents

Complex 1Complex 1

Has NADH binding siteHas NADH binding site– NADH reductase activityNADH reductase activity

NADH -NADH - NAD NAD++

– NADH ---> FMN--->FeS---> ubiquinoneNADH ---> FMN--->FeS---> ubiquinone

– ubiquinone ---> ubiquinone Hubiquinone ---> ubiquinone H22

– 4 H4 H++ pumped/NADH pumped/NADH

NAD+/NADHNADP+/NADPH

Never covalently bound- freely diffusible

Nicotinamide

Reaction at EnzymeReaction at Enzymereduced substrate + NAD(P)++ oxidized substrate + NAD(P)HH + H++

substrate relieved of two H atoms = hydride to NAD+ & H+ into solution

HydrideHydride = H-- = H: = H++ + 2e-

two electrons transferred reduced

NADH Dehydrogenase transfers electrons from NADH to CoQ, an electron carrier

Uses two bound cofactors toaccomplish this.

flavin and iron-sulfur center

Complex IIComplex II

succinate ---FAD—ubiquinonesuccinate ---FAD—ubiquinone– Contains coenzyme QContains coenzyme Q

– FADHFADH22 binding site binding site

FAD reductase activityFAD reductase activity

FADHFADH22 -- -- FAD FAD

For NADH, one of two entry points into the electron transport chain:

-- So the oxidation of one NADH results in the reduction of one CoQ-- Another important functionof the enzyme will be mentioned later.

Succinate DehydrogenaseSuccinate Dehydrogenase

-- similar reaction can be writtenyielding CoQH2

-- second entry into electron transport-- substrate is succinate-- FAD is reduced, not FMN

Flavin-linkedFlavin-linkedDehydrogenasesDehydrogenases

Flavin mononucleotide = FMNFlavin adenine dinucleotide = FAD

Riboflavin = ring + ribitol

Isoalloxazine ring

ribitol

Reduced form = FADH2

Transfer 2 H atoms with 2e-

or 2H

Reaction AH2 + E-FMN = A +E-FMNH2

2H+

+2e

Coenzyme QCoenzyme Q

Coenzyme Q = UbiquinoneCoenzyme Q = Ubiquinone

a lipid in inner membrane carries electrons polyisoprene tail moves freely within membrane

Complex IIIComplex III

ubiquinone -ubiquinone - ubiquinone ubiquinone oxox

while cyt C gets reducedwhile cyt C gets reduced

Also contains cytochromes bAlso contains cytochromes b– proton pump 4Hproton pump 4H++

Adds to gradientAdds to gradient– 8 H8 H++ / NADH / NADH

– 4 H4 H++ / FADH / FADH22

Cytochromes - proteins in Cytochromes - proteins in ETSETSCarry electronsContain hemeor heme-like groupHeme is based onporphyrins with ironin center, usuallyas Fe(II), and is tightlybound at sides,sometimes covalentlyContrast heme in cytochromes & hemoglobin

--For cytochrome heme,

  a) all 6 sites of Fe are filled(4 from porphyrin, 2 above andbelow from protein) = no moleculecan approach  b) carries electrons only: Fe(III) + eFe(III) + e-- Fe(II) Fe(II) Note: Only one electron is transferredat a time.

COMPLEX IIICOMPLEX III = b, an Fe-S and c1. Cytochrome cCytochrome c is mobile. COMPLEX IVCOMPLEX IV = a+a3 =

cytochrome a-acytochrome a-a33 =

cytochrome c oxidase cytochrome c oxidase -- large protein. -- both a and a3 contain heme A and Cu-- a3 Cu binds to oxygen and donates electrons to oxygencytochrome acytochrome a33 - only component ofETS that can interact with O2

Complex IVComplex IVreduction of oxygenreduction of oxygen

cytochrome oxidasecytochrome oxidase

cyt a+a3 cyt a+a3 redred ---> oxidized state ---> oxidized state

oxygen ---> wateroxygen ---> water– 2 H2 H++ + 2 e + 2 e-- + ½ O + ½ O22 -- -- 2 H 2 H22OO

– transfers etransfers e-- one at a time to oxygen one at a time to oxygen

Pumps 2HPumps 2H++ out out– Total of 10 HTotal of 10 H++ / NADH / NADH

– Total of 6 HTotal of 6 H++ / FADH / FADH22

What about NADH from glycolysis?What about NADH from glycolysis?

NADH made in cytosolNADH made in cytosol

Can’t get into matrix of Can’t get into matrix of mitochondrionmitochondrion

2 mechanisms2 mechanisms– In muscle and brainIn muscle and brain

Glycerol phosphate shuttleGlycerol phosphate shuttle

– In liver and heartIn liver and heartMalate / aspartate shuttleMalate / aspartate shuttle

Glycerol Phosphate shuttleGlycerol Phosphate shuttle

http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-3/ch19_glycerol-shuttle.jpghttp://courses.cm.utexas.edu/jrobertus/ch339k/overheads-3/ch19_glycerol-shuttle.jpg

Glycerol phosphate shuttleGlycerol phosphate shuttle

In muscle and brainIn muscle and brain

Each NADH converted to FADHEach NADH converted to FADH22 inside mitochondrioninside mitochondrion– FADHFADH22 enters later in the electron enters later in the electron

transport chaintransport chain– Produces 1.5 ATPProduces 1.5 ATP

Total ATP per glucose in muscle Total ATP per glucose in muscle and brain and brain

Gycerol phosphate shuttleGycerol phosphate shuttle– 2 NADH per glucose -2 NADH per glucose - 2 FADH 2 FADH22

– 2 FADH2 FADH22 X 1.5 ATP / FADH X 1.5 ATP / FADH22……….3.0 ATP……….3.0 ATP

– 2 ATP in glycoysis2 ATP in glycoysis ……………………2.0 ……………………2.0 ATPATP

– From pyruvate and KrebsFrom pyruvate and Krebs12.5 ATP X 2 per glucose ……………..12.5 ATP X 2 per glucose ……………..25.0 ATP25.0 ATP

Total = 30.0 ATP/ glucoseTotal = 30.0 ATP/ glucose

Malate – Aspartate ShuttleMalate – Aspartate Shuttlein cytosolin cytosol

In liver and heartIn liver and heart

NADH oxidized while reducing NADH oxidized while reducing oxaloacetate to malateoxaloacetate to malate– Malated dehydrogenaseMalated dehydrogenase

Malate crosses membraneMalate crosses membrane

Total ATP per glucose in liver and Total ATP per glucose in liver and heart heart

Malate – Aspartate ShuttleMalate – Aspartate Shuttle– 2 NADH per glucose -2 NADH per glucose - 2 NADH 2 NADH– 2 NADH X 2.5 ATP / NADH…………5.0 ATP2 NADH X 2.5 ATP / NADH…………5.0 ATP– 2 ATP from glycolysis………………..2.0 ATP2 ATP from glycolysis………………..2.0 ATP– From pyruvate and KrebsFrom pyruvate and Krebs

12.5 ATP X 2 per glucose ……………..12.5 ATP X 2 per glucose ……………..25.0 ATP25.0 ATP

Total = 32.0 ATP/ glucoseTotal = 32.0 ATP/ glucose

SummarySummary

Total ATP / glucoseTotal ATP / glucose– Muscle and brainMuscle and brain 30.0 ATP30.0 ATP

Uses glycerol phosphate shuttleUses glycerol phosphate shuttle

– Heart and liverHeart and liver 32.0 ATP32.0 ATPUses malate aspartate shuttleUses malate aspartate shuttle

Chemiosmotic TheoryChemiosmotic Theory --Peter Mitchell -- A proton gradientproton gradient isgenerated with energyfrom electron transportby the vectorial transportof protons (protonprotonpumpingpumping) by Complexes I,III, IV from the matrix tointermembrane spaceof the mitochondrion.

-- The protons have a thermodynamictendency to return to the matrix =Proton-motive forceProton-motive forceThe proton move back into the matrixthrough theFoF1ATPsynthasedrivingATP synthesis.

The proton pumps are Complexes Complexes I,I, III and IV.III and IV.

Protons return thru ATP synthase

Chemiosmotic PhosphorylationChemiosmotic Phosphorylation

Hydrogen ions travel down their concentration gradient through a channel Hydrogen ions travel down their concentration gradient through a channel protein coupled with an enzyme called protein coupled with an enzyme called ATP SynthaseATP Synthase..As HAs H++ ions move into the matrix, energy is released and used to combine ions move into the matrix, energy is released and used to combine ADP + P ADP + P → → ATP.ATP.Hydrogens are recycled and pumped back across the cristae using the Hydrogens are recycled and pumped back across the cristae using the Electron Transport Chain.Electron Transport Chain.ATP diffuses out of the mitochondria through channel proteins to be used ATP diffuses out of the mitochondria through channel proteins to be used by the cell.by the cell.

http://vcell.ndsu.nodak.edu/animations/atpgradient/movie.htm

ATP SynthaseATP SynthaseMultisubunit complex Multisubunit complex with 4 parts:with 4 parts:– RotorRotor – spins as H – spins as H++ ions flow ions flow– StatorStator – holds the rotor and – holds the rotor and

knob complex together in the knob complex together in the cristaecristae

– Internal RodInternal Rod – extends – extends between rotor and knob, spins between rotor and knob, spins when rotor spins which then when rotor spins which then turns the knobturns the knob

– KnobKnob – contains 3 catalytic – contains 3 catalytic sites that when turned change sites that when turned change shape and activate the enzyme shape and activate the enzyme used to make ATPused to make ATP

The return of protons “downhill”through Fo rotates Fo relative to F1,driving ATPsynthesis.Note: Subunit rotatesthrough F1.

All Types of Molecules can be used All Types of Molecules can be used to form ATP by Cell Respiration: to form ATP by Cell Respiration:

Proteins, Carbohydrates, Proteins, Carbohydrates, and Lipids must first be and Lipids must first be broken down into their broken down into their monomers and absorbed monomers and absorbed in the small intestine.in the small intestine.

Monomers may be Monomers may be further broken down into further broken down into intermediate molecules intermediate molecules before entering different before entering different parts of Cell respiration parts of Cell respiration to ultimately form ATP.to ultimately form ATP.

Review ATP Production:Review ATP Production:1) Glycolysis 1) Glycolysis → → 2 ATP2 ATP2) Oxidation of Pyruvate 2) Oxidation of Pyruvate → → No ATPNo ATP3) The Krebs Cycle 3) The Krebs Cycle → → 2 ATP2 ATP4) The Electron Transport Chain and 4) The Electron Transport Chain and

Chemiosmotic Phosphorylation: Chemiosmotic Phosphorylation: – Each NADH produces 2-3 ATP so 10 Each NADH produces 2-3 ATP so 10

NADH NADH →→ 28 ATP 28 ATP– Each FADHEach FADH22 produces 2 ATP so 2 produces 2 ATP so 2

FADHFADH22 → → 4 ATP4 ATP Total = 36 ATPTotal = 36 ATP

1 Glucose = 686 kcal1 Glucose = 686 kcal1 ATP = 7.3 kcal1 ATP = 7.3 kcal1 Glucose 1 Glucose → → 36 ATP36 ATPHow efficient are cells at converting How efficient are cells at converting glucose into ATP?glucose into ATP?– 38% of the energy from glucose 38% of the energy from glucose

yields ATP, therefore 62% wasted as yields ATP, therefore 62% wasted as heat (used to maintain body heat (used to maintain body temperature or is dissipated)temperature or is dissipated)

– Ex. Most efficient Cars: only 25% of Ex. Most efficient Cars: only 25% of the energy from gasoline is used to the energy from gasoline is used to move the car, 75% heat.move the car, 75% heat.

How is amount ATP synthesizedHow is amount ATP synthesized measured?measured?

Quantify P/O ratio Definition: # Pi taken up inphosphorylating ADP per atomoxygen (½O2), in other wordsper 2e-. NADH 3 FADH2 2

Anaerobic Respiration: FermentationAnaerobic Respiration: FermentationIf there is NO oxygen, then cells can make ATP by If there is NO oxygen, then cells can make ATP by FermentationFermentationWithout oxygen, Oxidation of Pyruvate and the Electron Transport Without oxygen, Oxidation of Pyruvate and the Electron Transport Chain do not operate.Chain do not operate.

Glucose Glucose →→ Pyruvate Pyruvate →→ Lactate Lactate NADNAD++ GlycolysisGlycolysis 2 NADH 2 NADH Reduction RxnReduction Rxn or or

2 ATP 2 ATP Alcohol + CO Alcohol + CO22

Fermentation yields a net gain of 2 ATP by substrate level phosphorylation Fermentation yields a net gain of 2 ATP by substrate level phosphorylation for every 1 Glucose. (Inefficient)for every 1 Glucose. (Inefficient)

Two Forms of FermentationTwo Forms of Fermentation: : Lactic Acid Fermentation (animals)Lactic Acid Fermentation (animals)Alcohol Fermentation (yeast)Alcohol Fermentation (yeast)

Inhibitors and Uncouplers: The Inhibitors and Uncouplers: The Difference is ImportantDifference is Important

Table 19-4 Lehninger POB 3Table 19-4 Lehninger POB 3rdrd Ed. Ed.