Notes Respiration 2010

8/6/2019 Notes Respiration 2010

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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

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Notes Respiration 2010