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Cellular RespirationCellular RespirationGetting Energy From FoodGetting Energy From Food
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Organisms Need EnergyOrganisms Need Energy
Energy entersEnergy enters
ecosystem asecosystem as
sunlight,sunlight,
leaves as heatleaves as heat
Matter isMatter is
recycledrecycled
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Harvesting Chemical EnergyHarvesting Chemical Energy
Glucose is the modelGlucose is the model
catabolismcatabolism of glucose to produce ATPof glucose to produce ATP
glucose+ oxygen energy + water + carbondioxide
resp
irat
ion
C6H12 O6 6O2 ATP 6H2O 6CO2+ + +
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Moving electrons in respirationMoving electrons in respiration
High energy foodHigh energy foodmoleculesmolecules
CarbohydratesCarbohydrates
FatsFats Give off energy asGive off energy as
they are brokenthey are broken
downdown
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Overview of cellular respirationOverview of cellular respiration
3 metabolic stages3 metabolic stages1.1. GlycolysisGly
colysis
2.2. Krebs cycleKrebs cy
cle
3.3. Electron transport chainElectron transp
ort chain
C6H12 O6 6O2 ATP 6H2O 6CO2+ + + (+ heat)
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GlycolysisGlycolysis
Anaerobic respirationAnaerobic resp
iration
One Step: GlycolysisOne Step: Glycolysis
Aerobic respirationAerobic resp
iration
- Begins with glycolysis- Begins with glycolysis If enough OIf enough O22 present in the cell,present in the cell,
moves on to steps 2 & 3moves on to steps 2 & 3
Next phases: in mitochondriaNext phases: in mitochondria
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GlycolysisGlycolysis
glucosepyruvate2x6C 3C
In thecytosol?Why doesthat make
evolutionarysense?
Breaking down glucoseBreaking down glucoseglycoglyco lysislysis(splitting sugar)(splitting sugar)
ancient pathway that harvests energyancient pathway that harvests energy where energy transfer first evolvedwhere energy transfer first evolved
transfer energy from organic molecules to ATPtransfer energy from organic molecules to ATP
still is starting point forstill is starting point for ALLALL cellular respirationcellular respiration
but its inefficientbut its inefficient generate onlygenerate only 2 ATP2 ATP for everyfor every 1 glucose1 glucose
occurs in cytoplasmoccurs in cytoplasm
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Pyruvate is a branching pointPyruvate is a branching point
PyruvatePyruvate
O2O2
mitochondriaKrebs cycle
aerobic respiration
fermentationanaerobicrespiration
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Any Questions???Any Questions???
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Citric Acid CycleCitric Acid Cycle
Oxygen present? Into themitochondrion!
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Pyruvate oxidized to Acetyl CoAPyruvate oxidized to Acetyl CoA
Yield =2C sugar+NADH+CO2
reductio
n
oxidatio
nC-C-C C-C
2 x [ ]
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4C
6C
4C
4C
4C
2C
6C
5C
4C
CO2
CO2
citrate
acetyl CoA
Count the carbons!
3Cpyruvate
x2
oxidationof sugars
This happens
twice for each
glucose
molecule
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So we completely brokedown glucose
C6
H12
O6
CO2
& ended up
withNet gain =2 ATP
=8 NADH + 2FADH2
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Oxidative PhosphorylationOxidative Phosphorylation
(Electron Transport)(Electron Transport) Electron TransportElectron Transport
ChainChain
series of proteins builtseries of proteins built
intointoinner mitochondrialinner mitochondrialmembranemembranealongalong cristaecristae
yieldsyields ~34 ATP~34 ATP from 1from 1
glucoseglucose!!
only in presence of Oonly in presence of O22
((aerobic respirationaerobic respiration))
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MitochondriaMitochondria
Double membraneDouble membrane outer membraneouter membrane
inner membraneinner membranehighly foldedhighly folded cristaecristae
enzymes & transportenzymes & transport
proteinsproteins
intermembrane spaceintermembrane space
fluid-filled spacefluid-filled spacebetween membranesbetween membranes
Matrix
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H+
H+ H+
H+
H+ H+
H+H+H+
ATP
NAD+
Q
C
NADH H2O
H+
e
2H+ + O2
H+H+
e FADH21
2NADH
dehydrogenase
cytochrome
bccomplex
cytochrome c
oxidase complex
FAD
e
The Electron Transport ChainThe Electron Transport Chain
Electron carriers pass electrons & HElectron carriers pass electrons & H++
toto
ETCETC--electrons passed from one electron carrier to nextelectrons passed from one electron carrier to next
flowing electrons = energy to do workflowing electrons = energy to do work
transport proteins pumptransport proteins pump HH++ ((protonsprotons) across inner) across innermembrane tomembrane to intermembrane spaceintermembrane space
ADP
+ Pi
H+ H+ H+
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The Electron Transport ChainThe Electron Transport Chain
O2
H2O
A h d f hAt th d f th
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H
+
ADP + Pi
H+ H+
H+
H+H+
H+H+H+
At the end of theAt the end of the
transport chaintransport chain
ChemiosmosisChemiosmosis
ATP
Set up a HSet up a H++ gradientgradient
Allow theAllow the protonsprotonsto flow through ATPto flow through ATP
synthasesynthase Synthesizes ATPSynthesizes ATP
ADPADP + P+ Pii ATPATP
Chemiosmosis
links the Electron
Transport Chain
to ATP synthesis
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H+
H+
O2+
QC
ATP
Pyruvate from
cytoplasm
Electrontransport
system
ATPsynthase
H2O
CO2
Krebs
cycle
Intermembrane
spaceInner
mitochondrial
membrane
1. Electrons are harvestedand carried to thetransport system.
2. Electronsprovide energy
to pumpprotons acrossthe membrane.
3. Oxygen joinswith protons andelectrons to formwater. 2H+
NADH
NADH
Acetyl-CoA
FADH2
ATP
4. Protons diffuse back indown their concentrationgradient, driving the
synthesis ofATP.
Mitochondrial
matrix
21
H+
H+
O2
H+
e-
e-
e-
e-
ATP
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Summary of cellular respirationSummary of cellular respiration
Where did the glucose come from?Where did the glucose come from?
Where did the OWhere did the O22 come from?come from? Where did the COWhere did the CO22 come from?come from?
Where did the COWhere did the CO22 go?go?
Where did the HWhere did the H22O come from?O come from?
Where did the ATP come from?Where did the ATP come from? What else is produced that is not listedWhat else is produced that is not listed
in this equation?in this equation? Why do we breathe?Why do we breathe?
C6H12 O6 6O2 6CO2 6H2O ~36 ATP+ + +
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Cellular RespirationCellular RespirationOther MetabolitesOther Metabolites
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Respiration canRespiration can
also break downalso break down
Other carbsOther carbs
FatsFats
ProteinsProteinsSmall pieces of theseSmall pieces of these
molecules enter atmolecules enter at
various stages ofvarious stages ofrespiration.respiration.
Beyond GlucoseBeyond Glucose
CO2
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Any Questions?Any Questions?
2 2 32
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Alcohol FermentationAlcohol Fermentation
Pyruvate decarboxylase (an enzyme in thePyruvate decarboxylase (an enzyme in thecytoplasm) removes a COcytoplasm) removes a CO22 from pyruvate,from pyruvate,
converting it into ethanol, the alcohol foundconverting it into ethanol, the alcohol found
in alcoholic beverages.in alcoholic beverages.
PyruvatePyruvate COCO22 + ethyl alcohol + 2ATP+ ethyl alcohol + 2ATP
Ex: making bread, beer and wineEx: making bread, beer and wine
Ethanol fermentationcreates ethanol,CO2, and ATP fromglucose.
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Lactic Acid FermentationLactic Acid Fermentation
During strenuous exercise, muscle cellsDuring strenuous exercise, muscle cellsbreak down glucose faster than oxygenbreak down glucose faster than oxygen
can be supplied.can be supplied.
Lactate dehydrogenase (an enzyme inLactate dehydrogenase (an enzyme inthe cytoplasm) then converts pyruvatethe cytoplasm) then converts pyruvate
into lactate.into lactate.
PyruvatePyruvate COCO22 + lactic acid + 2ATP+ lactic acid + 2ATPEx: sore musclesEx: sore muscles
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Lactic Acid FermentationLactic Acid Fermentation
The accumulation of lactate molecules inThe accumulation of lactate molecules inmuscle tissue causes stiffness, soreness,muscle tissue causes stiffness, soreness,and fatigue.and fatigue.
Lactate is converted back to pyruvate whenLactate is converted back to pyruvate whenvigorous exercise ends but requiresvigorous exercise ends but requiresoxygen.oxygen.
Rigor mortisRigor mortis is caused by the fermentationis caused by the fermentationof glucose in muscle cells, leading to highof glucose in muscle cells, leading to highlevels of lactic acid. The lactic acid causeslevels of lactic acid. The lactic acid causesmuscle tissue to become rigid.muscle tissue to become rigid.
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Organisms that use anaerobicOrganisms that use anaerobic
respirationrespiration Yeast (single celled fungi) produceYeast (single celled fungi) produce
COCO22to make bread rise. Also produceto make bread rise. Also produce
alcohol.alcohol.
Many bacteriaMany bacteria
Lactic acid can be produced in animalLactic acid can be produced in animal
muscle cellsmuscle cells