BIOL 222 Ch 9 Cellular Respiration part 2...
Transcript of BIOL 222 Ch 9 Cellular Respiration part 2...
1
Fig.9-12-2
Acetyl CoA
Oxaloacetate
Citrate
CoA—SH
Citric acid cycle
1
2
H2O
Isocitrate
Fig.9-12-3
Acetyl CoACoA—SH
Oxaloacetate
Citrate
H2O
Citric acid cycle
Isocitrate
1
2
3
NAD+
NADH+ H+
α-Keto- glutarate
CO2
Fig.9-12-4
Acetyl CoACoA—SH
Oxaloacetate
Citrate
H2O
IsocitrateNAD+
NADH+ H+
Citric acid cycle
α-Keto- glutarate
CoA—SH
1
2
3
4
NAD+
NADH+ H+Succinyl
CoA
CO2
CO2
2
Fig.9-12-5
Acetyl CoACoA—SH
Oxaloacetate
Citrate
H2O
IsocitrateNAD+
NADH+ H+
CO2
Citric acid cycle
CoA—SH
α-Keto- glutarate
CO2NAD+
NADH+ H+Succinyl
CoA
1
2
3
4
5
CoA—SH
GTP GDP
ADP
P iSuccinate
ATP
Fig.9-12-6
Acetyl CoACoA—SH
Oxaloacetate
H2O
CitrateIsocitrate
NAD+
NADH+ H+
CO2
Citric acid cycle
CoA—SH
α-Keto- glutarate
CO2NAD+
NADH+ H+
CoA—SH
PSuccinyl
CoA
iGTP GDP
ADP
ATP
SuccinateFAD
FADH2
Fumarate
1
2
3
4
5
6
Fig.9-12-7
Acetyl CoACoA—SH
Oxaloacetate
Citrate
H2O
IsocitrateNAD+
NADH+ H+
CO2
α-Keto- glutarate
CoA—SH
NAD+
NADHSuccinyl
CoA
CoA—SH
PP
GDPGTP
ADP
ATP
SuccinateFAD
FADH2
Fumarate
Citric acid cycleH2O
Malate
1
2
5
6
7
i
CO2
+ H+
3
4
3
Fig.9-12-8
Acetyl CoACoA—SH
Citrate
H2O
IsocitrateNAD+
NADH+ H+
CO2
α-Keto- glutarate
CoA—SH
CO2NAD+
NADH+ H+Succinyl
CoA
CoA—SH
P iGTP GDP
ADP
ATP
SuccinateFAD
FADH2
Fumarate
Citric acid cycleH2O
Malate
Oxaloacetate
NADH+H+
NAD+
1
2
3
4
5
6
7
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ElectronTransport• Electrontransportchain
• Ontheinnermembrane(cristae)ofthemitochondrion
• MostlyinmulFproteincomplexes
• Carriersalternatereducedandoxidizedstates
• astheyacceptanddonateelectrons
• Electronbucketbrigade
• Electrons
• Dropinfreeenergyastheygodownthechain
• FinallypassedtoO2,formingH2O
NADH
NAD+2FADH2
2 FADMultiprotein complexesFAD
Fe•SFMN Fe•S
Q
Fe•S
Ι
Cyt b
ΙΙ
ΙΙΙ
Cyt c1
Cyt cCyt a
Cyt a3
IV
Free
ene
rgy
(G) r
elat
ive
to O
2 (kc
al/m
ol)
50
40
30
20
10 2(from NADH
or FADH2)
0 2 H+ + 1/2 O2
H2O
e–
e–
e–
• Electrontransportchain
• generatesnoATP(directly)
• ButcreatesH+gradient
• Concentratedinthe
intermembranespace
• breaksthelargefree-energydrop
fromglucosetoO2
• intosmallerstepsthatrelease
energyinmanageableamounts
ElectronTransportChain
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Chemiosmosis:TheEnergy-CouplingMechanism• H+intheintermembranespace
• thenmovebackacrossthemembrane
• DownconcentraFongradient
• passingthroughchannelsinATP
synthase
• ATPsynthase
• usestheexergonicflowofH+todrive
phosphorylaFonofATP
• ThisisChemiosmosis
• TheuseofenergyinaH+gradienttodrive
cellularwork
INTERMEMBRANE SPACE
Rotor
H+
Stator
Internal rod
Cata- lytic knob
ADP+P ATP
i
MITOCHONDRIAL MATRIX
• TheenergystoredinaH+gradient
• CouplestheredoxreacFonsoftheelectrontransportchaintoATP
synthesis
• Proton-mo:veforce
• PotenFalenergyintheH+gradient
• Representsitscapacitytodowork
ThePathwayofElectronTransport
Fig.9-16
Protein complex of electron carriers
H+
H+H+
Cyt c
Q
Ι
ΙΙ
ΙΙΙ
ΙV
FADH2 FAD
NAD+NADH(carrying electrons from food)
Electron transport chain
2 H+ + 1/2O2 H2O
ADP + P i
Chemiosmosis
Oxidative phosphorylation
H+
H+
ATP synthase
ATP
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PLAY
5
AerobicRespira:onSummary
• Energyflowsinthissequence:
glucose→NADH →electrontransportchain→proton-moFveforce→ATP
• About37%oftheenergyinaglucosemoleculeistransferredtoATPduring
cellularrespiraFon
• Makesabout38ATP
• 36net!(inprokaryotes)
• Actuallyabout30inEukaryotes
• Roughly3ATPperreducedelectroncarrier
• InaddiFontoATPformedbysubstratelevelphosphorylaFon
Fig.9-17
Maximum per glucose: About 36 or 38 ATP
+ 2 ATP+ 2 ATP + about 32 or 34 ATP
Oxidative phosphorylation: electron transport
and chemiosmosis
Citric acid cycle
2 Acetyl CoA
Glycolysis
Glucose2
Pyruvate
2 NADH 2 NADH 6 NADH 2 FADH2
2 FADH2
2 NADHCYTOSOL Electron shuttles
span membraneor
MITOCHONDRION
Fermenta:onandanaerobicrespira:on• AerobiccellularrespiraFonrequiresO2to
produceATP
• Glycolysis
• canproduceATPwithorwithoutO2
• inaerobicoranaerobiccondiFons
• WithoutO2
• Electrontransportchaincan’treleaseelectrons
• Systembacksupandshutsdown
• Glycolysiscoupleswithfermenta:onoranaerobicrespira:ontoproduceATP
NADH
NAD+2FADH2
2 FADMultiprotein complexes
FADFe•S
FMN Fe•
S Q
Fe•S
Ι
Cyt b
ΙΙ
ΙΙΙ
Cyt c1
Cyt cCyt a
Cyt a3
IV
Free
ene
rgy
(G) r
elat
ive
to O
2 (kc
al/
mol
)
50
40
30
20
10 2(from
NADH or FADH2)
0 2 H+ + 1/2 O2
H2O
e–
e–
e–
6
• AnaerobicrespiraFon
• usesETCwithanelectron
acceptorotherthanO2
• sulfate
• FermentaFon
• usessubstratelevel
phosphorylaFon
• insteadofanelectron
transportchainto
generateATP
Fermenta:onandanaerobicrespira:on
TypesofFermenta:on• FermentaFon
• Consistsofglycolysisplus
reacFonsthatregenerateNAD+
• Tobereusedbyglycolysis
• Twocommontypes
• alcoholfermentaFon
• Plants,fungi,bacteria
• lacFcacidfermentaFon
• Animalsandafewbacteria
andfungi
• Alcoholfermenta:on
• Pyruvateis
convertedto
ethanolintwosteps
• firstreleases
CO2
• Usedbyyeastinbrewing,
winemaking,andbaking
Fermenta:on
2 ADP + 2 P i 2 ATP
Glucose Glycolysis
2 Pyruvate
2 NADH2 NAD+
+ 2 H+CO2
2 Acetaldehyde2 Ethanol
(a) Alcohol fermentation
2
7
• Lac:cacidfermenta:on
• PyruvateisreducedbyNADH
• formslactateasanendproduct
• noreleaseofCO2
• Usedbysomefungiandbacteriatomakecheeseandyogurt
• Humanmusclecells
• usetogenerateATPwhenO2isscarceorabsent
• Earlyinstrenuousexerciseassugarcatabolismoutpacesoxygendelivery
Fermenta:onandanaerobicrespira:on
Glucose
2 ADP + 2 P i 2 ATP
Glycolysis
2 NAD+ 2 NADH+ 2 H+
2 Pyruvate
2 Lactate
(b) Lactic acid fermentation
Fermenta:onandAerobicRespira:onCompared• Bothprocesses
• Useglycolysistooxidizeglucoseandotherorganicfuelstopyruvate
• Havedifferentfinalelectronacceptors:
• FermentaFon
• anorganicmolecule
• pyruvateoracetaldehyde
• AerobicCellularrespiraFon
• O2
• CellularrespiraFon
• Produces36(or30(38))ATPperglucosemolecule
• FermentaFon
• Produces2(4)ATPperglucosemolecule
• Obligateanaerobes
• carryoutfermentaFonoranaerobic
respiraFon
• cannotsurviveinthepresenceofO2
• Faculta:veanaerobes
• Yeastandmanybacteria
• cansurviveusingeitherfermentaFon
orcellularrespiraFon
• pyruvateisaforkinthemetabolicroad
• thatleadstotwoalternaFvecatabolic
routes
Fermenta:onandanaerobicrespira:on
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Fig.9-19
Glucose
Glycolysis
Pyruvate
CYTOSOL
No O2 present: Fermentation
O2 present: Aerobic cellular respiration
MITOCHONDRIONAcetyl CoAEthanol
or lactate
Citric acid cycle
TheVersa:lityofCatabolism• Catabolicpathways
• funnelelectronsfrommanykindsoforganicmoleculesintocellular
respiraFon
• Glycolysis
• acceptsawiderangeofcarbohydrates
• Notjustglucoseorpolymersofglucose
• Proteins
• mustbedigestedtoaminoacids
• aminoacidscanfeedglycolysisorthecitricacidcycle
• Mustbedeaminatedfirst
• Fatsdigestedto
• glycerol(usedinglycolysis)
• convertedtoG3P
• fafyacids(usedingeneraFngacetylCoA)
• Fafyacids
• brokendownbybetaoxida:on
• yield2-carbonfragments
• becomesacetylCoA
• AlsoyieldssomeNADHandFADH2
• AnoxidizedgramoffatproducesmorethantwiceasmuchATPasanoxidizedgramofcarbohydrate
TheVersa:lityofCatabolismProteins Carbohydrates
Amino acids
Sugars
Fats
Glycerol Fatty acids
Glycolysis
Glucose
Glyceraldehyde-3-
Pyruvate
P
NH3
Acetyl CoA
Citric acid cycle
Oxidative phosphorylation
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Regula:onofCellularRespira:on
• FeedbackinhibiFon
• Mostcommonmechanismforcontrol
• ATPconcentraFon
• beginstodrop,respiraFonspeedsup
• plentyofATP,respiraFonslowsdown
• Controlofcatabolism
• basedmainlyonregulaFngtheacFvityofenzymes
• Atstrategicpointsinthecatabolicpathway
Glucose
GlycolysisFructose-6-phosphate
Phosphofructokinase
Fructose-1,6-bisphosphateInhibits
AMP
Stimulates
Inhibits
Pyruvate
CitrateAcetyl CoA
Citric acid cycle
Oxidative phosphorylation
ATP
+
––
Regula:onofCellularRespira:onviaFeedbackMechanisms
• Phosphofructokinase
• Majorswitchinglycolysis
• Substratenowcommifedto
glycolysis
• PacemakerofrespiraFon
• Allostericenzyme
• InhibitedbyATP,citrate
• SFmulatedbyAMP
Youshouldnowbeableto:
1. ExplainingeneraltermshowredoxreacFonsareinvolvedinenergyexchanges
2. NamethethreestagesofcellularrespiraFon;foreach,statethe
regionoftheeukaryoFccellwhereitoccursandtheproductsthatresult
3. Ingeneralterms,explaintheroleoftheelectrontransportchainincellularrespiraFon
4. Explainwhereandhowtherespiratoryelectrontransportchain
createsaprotongradient
5. DisFnguishbetweenfermentaFonandanaerobicrespiraFon