Download - Ch. 9 Cellular Respira,on

CellularRespira,onCellularRespira,onBIOL222

Ch.9

EnergyEnergy

Lightenergy

ECOSYSTEM

Photosynthesis in chloroplasts

CO2 + H2O

Cellular respirationin mitochondria

Organicmolecules +

O2

ATP powers most cellular work

Heatenergy

ATP

• Energy

• Arrivesassunlight

• Photosynthesis

• Plantscapturesunlight

• organicmoleculesandgeneratesO2

• Carbsusedincellularrespira@on

• Cellsuseenergystoredinorganicmolecules

• toregenerateATP

• Energyeventuallyleavesasheat

CatabolicPathwaysandProduc,onofATPCatabolicPathwaysandProduc,onofATP

• Thebreakdownoforganicmoleculesisexergonic

• Aerobicrespira,on

• ConsumesorganicmoleculesandO2andyieldsATP

• Typicallyglucose

• Fermenta,on

• Par@aldegrada@onofsugarsthatoccurswithoutO2

• Anaerobicrespira,on

• similartoaerobicrespira@on

• butusescompoundsotherthanO2asthefinalelectronacceptor

• Cellularrespira,on

• includesbothaerobicandanaerobicrespira@onbutisoGenusedto

refertoaerobicrespira@on

• 3of4macromoleculeclassesmaybeusedasfuel

• carbohydrates,fats,andproteins

C6H12O6+6O2→6CO2+6H2O+Energy(ATP+heat)

CellularRespira,onCellularRespira,on

ThePrincipleofRedoxThePrincipleofRedox

• oxida@on‐reduc@onreac@ons

• Chemicalreac@onsthattransferelectronsbetweenreactantsarecalled

• redoxreac,ons

• Oxida,on

• asubstanceloseselectrons

• isoxidized

• Reduc,on

• asubstancegainselectron

• isreduced(theamountofposi@vechargeisreduced)

• OIL‐RIG

becomes oxidized(loses electron)

becomes reduced(gains electron)

• Reducingagent

• electrondonor

• Oxidizingagent

• electronreceptor

• Someredoxrxnsdonot

transferelectrons

• butchangetheelectron

sharingincovalentbonds

• exampleisthereac@on

betweenmethaneandO2

ThePrincipleofRedoxThePrincipleofRedox

Reactants

becomes oxidized

becomes reduced

Products

Methane(reducing

agent)

Oxygen(oxidizing

agent)

Carbon dioxide Water

Oxida,onDuringCellularRespira,onOxida,onDuringCellularRespira,on

• Duringcellularrespira@on,thefuel(suchasglucose)isoxidized,and

O2isreduced:

becomes oxidized

becomes reduced

NADNAD++andtheElectronTransportChainandtheElectronTransportChain• Glucoseandotherorganicmolecules

• Brokendowninaseriesofsteps

• NAD+(nico@namideadeninedinucleo@de)

• Electroncarrier

• Electronsfromorganiccompoundstransferred

• func@onsasanoxidizingagentduringcellularrespira@on

• NADH

• ReducedformofNAD+

• representsstoredenergythatisusedtosynthesizeATP

Dehydrogenase

Fig.9‐4Fig.9‐4

Dehydrogenase

Reduction of NAD+

Oxidation of NADH

2 e– + 2 H+

2 e– + H+

NAD+ + 2[H]

NADH

+

H+

H+

Nicotinamide(oxidized form)

Nicotinamide(reduced form)

• NADH

• Deliverselectronstotheelectrontransportchain(ETC)

• ETCpasseselectronsinaseriesofsteps

• insteadofoneexplosivereac@on

• Slow,controlledenergyrelease

• O2receiveselectronsfromtheETC

• AGeranenergy‐yieldingtumbledownthechain

• Finalelectronacceptor

• TheenergyyieldedisusedtoregenerateATP

NAD+andtheElectronTransportChainNAD+andtheElectronTransportChain

Free

ene

rgy,

G

Free

ene

rgy,

G

(a) Uncontrolled reaction

H2O

H2 + 1 /2 O2

Explosiverelease of

heat and lightenergy

(b) Cellular respiration

Controlledrelease ofenergy for

synthesis ofATP

2 H+ + 2 e–

2 H + 1/2 O2

(from food via NADH)

ATP

ATP

ATP

1/2 O22 H+

2 e–

Electron transport

chain

H2O

TheStagesofCellularRespira,on:TheStagesofCellularRespira,on:APreviewAPreview

• Cellularrespira@onhasthreestages:

• Glycolysis

• Literally“sugarbreaking”

• breaksdownglucoseintotwomoleculesofpyruvate

• Citricacidcycle

• completesthebreakdownofglucose

• AlsocalledKrebscycle

• Oxida,vephosphoryla,on

• accountsformostoftheATPsynthesis

• IncludesElectronTransportChain

Fig.9‐6‐1Fig.9‐6‐1

Substrate-levelphosphorylation

ATP

Cytosol

Glucose Pyruvate

Glycolysis

Electronscarried

via NADH

Fig.9‐6‐2Fig.9‐6‐2

Mitochondrion


ATP

Cytosol

Glucose Pyruvate

Glycolysis

Electronscarried

via NADH


ATP

Electrons carriedvia NADH and

FADH2

Citricacidcycle

Fig.9‐6‐3Fig.9‐6‐3

Mitochondrion


ATP

Cytosol

Glucose Pyruvate

Glycolysis

Electronscarried

via NADH


ATP

Electrons carriedvia NADH and

FADH2

Oxidativephosphorylation

ATP

Citricacidcycle

Oxidativephosphorylation:electron transport

andchemiosmosis

• Oxida,vephosphoryla,on

• accountsforalmost90%oftheATPgeneratedbycellularrespira@on

• 32of36‐38total

• substrate‐levelphosphoryla,on

• ATPformedinglycolysisandthecitricacidcycle

Oxida,veOxida,vePhosphoryla,onPhosphoryla,on

Enzyme

ADP

PSubstrate

Enzyme

ATP+

Product

GlycolysisGlycolysis

• Glycolysis

• Breaksdownglucoseintotwomoleculesofpyruvate

• Occursinthecytoplasm

• Twomajorphases:

• Energyinvestmentphase

• Energypayoffphase

Fig.9‐8Fig.9‐8

Energy investment phase

Glucose

2 ADP + 2 P 2 ATP used

formed4 ATP

Energy payoff phase

4 ADP + 4 P

2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

2 Pyruvate + 2 H2O

2 Pyruvate + 2 H2OGlucoseNet

4 ATP formed – 2 ATP used 2 ATP

2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

Fig.9‐9‐1Fig.9‐9‐1

ATP

ADP

Hexokinase1

ATP

ADP

Hexokinase1

Glucose

Glucose-6-phosphate

Glucose

Glucose-6-phosphate

Fig.9‐9‐2Fig.9‐9‐2

Hexokinase

ATP

ADP

1

Phosphoglucoisomerase2

Phosphogluco-isomerase

2

Glucose

Glucose-6-phosphate

Fructose-6-phosphate

Glucose-6-phosphate


1

Fig.9‐9‐3Fig.9‐9‐3

Hexokinase

ATP

ADP

Phosphoglucoisomerase

Phosphofructokinase

ATP

ADP

2

3

ATP

ADP

Phosphofructo-kinase

Fructose-1, 6-bisphosphate

Glucose

Glucose-6-phosphate



1

2

3


3

Fig.9‐9‐4Fig.9‐9‐4

Glucose

ATP

ADP

Hexokinase

Glucose-6-phosphate

Phosphoglucoisomerase


ATP

ADP

Phosphofructokinase


Aldolase

Isomerase

Dihydroxyacetonephosphate

Glyceraldehyde-3-phosphate

1

2

3

4

5

Aldolase

Isomerase


Dihydroxyacetonephosphate


4

5

Fig.9‐9‐5Fig.9‐9‐5

2 NAD+

NADH2+ 2 H+

2

2 Pi

Triose phosphatedehydrogenase

1, 3-Bisphosphoglycerate

6

2 NAD+



NADH2+ 2 H+

2 P i


6

2

2

Fig.9‐9‐6Fig.9‐9‐6

2 NAD+

NADH2


+ 2 H+

2 P i

22 ADP


Phosphoglycerokinase2 ATP

2 3-Phosphoglycerate

6

7

2

2 ADP

2 ATP


3-Phosphoglycerate

Phosphoglycero-kinase

2

7

Fig.9‐9‐7Fig.9‐9‐7

3-Phosphoglycerate


2 NAD+

2 NADH+ 2 H+

2 P i

22 ADP

Phosphoglycerokinase


2 ATP

3-Phosphoglycerate2

Phosphoglyceromutase

2-Phosphoglycerate2

2-Phosphoglycerate2

2

Phosphoglycero-mutase

6

7

8

8

Fig.9‐9‐8Fig.9‐9‐8

2 NAD+

NADH2

2

2

2

2

+ 2 H+


2 P i



2 ADP

2 ATP

3-Phosphoglycerate


Enolase

2-Phosphoglycerate

2 H2O

Phosphoenolpyruvate

9

8

7

6

2 2-Phosphoglycerate

Enolase

2

2 H2O

Phosphoenolpyruvate

9

Fig.9‐9‐9Fig.9‐9‐9


2 NAD+

NADH2

2

2

2

2

2

2 ADP

2 ATP

Pyruvate

Pyruvate kinase

Phosphoenolpyruvate

Enolase2 H2O

2-Phosphoglycerate


3-Phosphoglycerate


2 ATP

2 ADP


+ 2 H+

6

7

8

9

10

22 ADP

2 ATP

Phosphoenolpyruvate

Pyruvate kinase

2 Pyruvate

10

2 P i

IntermediateIntermediateStepStep• IfO2ispresent

• pyruvateentersthe

mitochondrion

• Twoperoriginalglucose

• acetylCoA

• PyruvateaddedtocoenzymeA

• becomesacetylcoA

• Asitcrossesthemito

membranes

• YieldsfirstCO2wastes

• ReducesaNAD+toNADH

• Entersthecitricacidcycle

CYTOSOL MITOCHONDRION

NAD+ NADH + H+

2

1 3

Pyruvate

Transport protein

CO2Coenzyme A

Acetyl CoA

• Citricacidcycle

• AlsocalledtheKrebscycle

• Occursinthemitochondrial

matrix

• Cycleoxidizesorganicfuelderived

frompyruvate

• generates1ATP,3NADH,

and1FADH2perturn

• Twiceperglucose!

CitricAcidCycleCitricAcidCycle

Pyruvate

NAD+

NADH

+ H+Acetyl CoA

CO2

CoA

CoA

CoA

Citricacidcycle

FADH2

FAD

CO22

3

3 NAD+

+ 3 H+

ADP + P i

ATP

NADH

• Citricacidcycle

• Eightsteps

• Eachcatalyzedbyaspecificenzyme

• AcetylgroupofacetylCoAjoinsthecyclebycombiningwithoxaloacetate

• Formingcitrate

• CoenzymeAreturnstointermediatestep

• Thenextsevenstepsdecomposethecitratebacktooxaloacetate

• Makestheprocessacycle

• TheNADHandFADH2

• Deliverelectronstotheelectrontransportchain

CitricAcidCycleCitricAcidCycle

Download - Ch. 9 Cellular Respira,on

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