How Cells Harvest Chemical Energy. ATP Is Universal Energy Source Photosynthesizers get energy from the sun Consumers get energy from plants or other

How Cells Harvest How Cells Harvest Chemical EnergyChemical Energy

ATP Is Universal Energy SourceATP Is Universal Energy Source Photosynthesizers get Photosynthesizers get

energy from the sunenergy from the sun

Consumers get energy Consumers get energy from plants or other from plants or other organismsorganisms

ENERGY is ALWAYS ENERGY is ALWAYS converted to the chemical converted to the chemical bond energy of ATPbond energy of ATP

Photosynthesis and Photosynthesis and Respiration are LINKEDRespiration are LINKED

PhotosynthesisPhotosynthesis Overall reaction:Overall reaction:

6 CO6 CO22 + 12 H + 12 H22O O C C6 6 HH1212OO6 6 + 6 O+ 6 O2 2 + 6 H+ 6 H22OO

Often shown asOften shown as6 CO6 CO22 + 6 H + 6 H22O O C C6 6 HH1212OO6 6 + 6 O+ 6 O2 2

PhotosynthesisPhotosynthesis

Light Dependent Reactions

Light-Independent Reactions

6 O2 Glucose-P + 6 H2O

ATP

NADPH

ADP + P

NADP+

Sunlight 12 H2O 6 CO2

Reactions occur in grana of the thylakoid membrane

system

Reactions occur in stroma

Cellular RespirationCellular Respiration

Glucose + 6 OGlucose + 6 O2 2 6 CO 6 CO22 + 6 H + 6 H22O + ATPO + ATP

Cellular respiration is the controlled Cellular respiration is the controlled breakdown of organic moleculesbreakdown of organic molecules– Energy is released in small amounts that can Energy is released in small amounts that can

be captured and stored in ATPbe captured and stored in ATP Aerobic respiration is ~40% efficientAerobic respiration is ~40% efficient Meaning…40% of the energy stored in the Meaning…40% of the energy stored in the

glucose is stored as ATPglucose is stored as ATP

Breathing

Lungs

Muscle cells carrying out

Cellular Respiration

Bloodstream

Glucose 6 O2

6 CO2 6 H2O 36-38 ATP

O2 CO2

CO2 O2

•Breathing and cellular respiration are Breathing and cellular respiration are closely related:closely related:

Cells tap energy from electrons “falling” from Cells tap energy from electrons “falling” from organic fuels to oxygenorganic fuels to oxygen

When the carbon-hydrogen bonds of glucose When the carbon-hydrogen bonds of glucose are broken, electrons are transferred to oxygenare broken, electrons are transferred to oxygen– Glucose loses its hydrogen atoms and is ultimately Glucose loses its hydrogen atoms and is ultimately

converted to COconverted to CO22

– At the same time, OAt the same time, O22 gains hydrogen atoms and is gains hydrogen atoms and is

converted to Hconverted to H22OO– In the process the energy released is used to make In the process the energy released is used to make

ATPATP

Copyright © 2009 Pearson Education, Inc.

How Cells Make ATPHow Cells Make ATP

ATP is made in two ways during cellular ATP is made in two ways during cellular respiration:respiration:

1.1. Substrate level phosphorylationSubstrate level phosphorylation GlycolysisGlycolysis Citric acid cycle (Krebs cycle)Citric acid cycle (Krebs cycle)

2.2. Oxidative phosphorylationOxidative phosphorylation Electrons transport system and chemiosmosisElectrons transport system and chemiosmosis

Fig. 9.7

ENZYME

Substrate

Substrate gives energyand phosphate group (Pi)to ADP and makes ATP

Makes small amount of ATP

Product

Substrate-level Substrate-level phosphorylation phosphorylation

Oxidative phosphorylationOxidative phosphorylation Electron carriers (NADH and FADHElectron carriers (NADH and FADH22) deliver ) deliver

electrons to the Electron Transport Chain (ETC) on electrons to the Electron Transport Chain (ETC) on the inner membrane of the mitochondriathe inner membrane of the mitochondria

Electrons are passed from membrane protein to Electrons are passed from membrane protein to protein in a series of oxidation reduction reactions.protein in a series of oxidation reduction reactions.• Each transfer releases energy (more to come on this)Each transfer releases energy (more to come on this)

Energy is used to create a chemical gradientEnergy is used to create a chemical gradient• Gradient is used to drive ATP synthesis by the enzyme Gradient is used to drive ATP synthesis by the enzyme

ATP synthaseATP synthase

Overview of Cellular Respiration

Carbohydrate MetabolismCarbohydrate Metabolism

The first pathway of carbohydrate The first pathway of carbohydrate metabolism is called glycolysis.metabolism is called glycolysis. GlucoseGlucose is the starting material for glycolysis. is the starting material for glycolysis. Glycolysis reactions occur in the cytoplasm.Glycolysis reactions occur in the cytoplasm.

GlycolysisGlycolysis

Step #1Step #1: Glucose is converted to glucose-: Glucose is converted to glucose-6-phosphate in a phosphorylation reaction6-phosphate in a phosphorylation reaction Reaction is endergonicReaction is endergonic Reaction requires an input of ATPReaction requires an input of ATP

Step #2Step #2: A rearrangement reaction occurs : A rearrangement reaction occurs to make fructose-6-phosphateto make fructose-6-phosphate


Step #3Step #3: Another phosphorylation reaction : Another phosphorylation reaction occurs to made fructose-1,6-diphosphateoccurs to made fructose-1,6-diphosphate Reaction is endergonicReaction is endergonic Reaction requires an input of ATPReaction requires an input of ATP

Step #4Step #4: Fructose-1,6-diphosphate is : Fructose-1,6-diphosphate is broken in to 2 three carbon compoundsbroken in to 2 three carbon compounds


5 more steps occur and 2 pyruvate are 5 more steps occur and 2 pyruvate are mademade These steps release energy and electrons.These steps release energy and electrons.

• Energy released is used to make ATP by Energy released is used to make ATP by substrate substrate level phosphorylationlevel phosphorylation

• Electrons are attached to the electron carrier NADElectrons are attached to the electron carrier NAD++ to form 2 NADHto form 2 NADH

The NADH deliver electrons and HThe NADH deliver electrons and H++ to the electron to the electron transport systemtransport system

More on NADHMore on NADH

Synthesis of NADH:Synthesis of NADH:

NADNAD++ + 2 e + 2 H + 2 e + 2 H++ NADH NADH

Is NADIs NAD++ oxidized or reduced in this reaction? oxidized or reduced in this reaction?


Energy requiring steps:Energy requiring steps: 2 ATP invested2 ATP invested

Energy releasing steps:Energy releasing steps:2 NADH formed 2 NADH formed

4 ATP formed4 ATP formed

Net yield is 2 ATP and 2 NADHNet yield is 2 ATP and 2 NADH

Does NOT require ODoes NOT require O22

Occurs in the cytoplasmOccurs in the cytoplasm

Glycolysis SummaryGlycolysis Summary

Where it occurs:Where it occurs: First substrate: First substrate: (starting “material”)(starting “material”)

End product:End product: Also made:Also made:

net gain of ____ ATP (why net?, how made?)net gain of ____ ATP (why net?, how made?) _____ NADH (made from?)_____ NADH (made from?)


Where it occurs: Where it occurs: CytoplasmCytoplasm

First Substrate:First Substrate: Glucose (6C)Glucose (6C)

End product:End product: 2 Pyruvate (3C)2 Pyruvate (3C)


Also madeAlso made net gain of net gain of 22 ATP ATP made by substrate-made by substrate-

level phosphorylationlevel phosphorylation

• Pathway requires an input of 2 ATP Pathway requires an input of 2 ATP to start and makes a total of 4 ATPto start and makes a total of 4 ATP

2 NADH – each made from NAD2 NADH – each made from NAD++ ,2e ,2e and Hand H++

Energy Releasing PathwaysEnergy Releasing Pathways

• What happens to the products of What happens to the products of glycolysis depends upon cell conditions.glycolysis depends upon cell conditions.

Aerobic conditionsAerobic conditions• Preparatory step and Citric Acid/Krebs Preparatory step and Citric Acid/Krebs

cyclecycle• Electron transport systemElectron transport system

Anaerobic conditionsAnaerobic conditions• FermentationFermentation

GLYCOLYSISGLYCOLYSIS

ANAEROBIC Conditions

No oxygen present

AEROBIC RESPIRATIONOxygen present

OR


ANAEROBIC • Fermentation occurs• Type depends upon cell type

AEROBIC RESPIRATION• Preparatory step• Krebs Cycle• Electron Transport System

OR


ANAEROBIC

ReactionsOccur in Cytoplasm

AEROBIC RESPIRATION

ReactionsOccur in Mitochondria

OR


ANAEROBIC

Net gain of 2 ATP

AEROBIC RESPIRATION

Net gain of 36-38 ATP

OR

Pathways ofPathways of Aerobic RespirationAerobic Respiration

1.1. GlycolysisGlycolysis

2.2. Krebs CycleKrebs Cycle Also called Citric Acid cycle Also called Citric Acid cycle

3.3. Electron Transport Chain and Electron Transport Chain and ChemiosmosisChemiosmosis

Aerobic RespirationAerobic Respiration

The first reaction occurs after The first reaction occurs after glycolysis is the Preparatory Stepglycolysis is the Preparatory Step This reaction occurs as the pyruvate This reaction occurs as the pyruvate

enter the matrix of the mitochondriaenter the matrix of the mitochondria

Preparatory StepPreparatory Step

As the pyruvate enter the mitochondria As the pyruvate enter the mitochondria each has a carbon removed and co-each has a carbon removed and co-enzyme A addedenzyme A added

Produced in the Prep. StepProduced in the Prep. Step• 2 NADH (go to ETS)2 NADH (go to ETS)

• 2 CO2 CO2 2 (diffuse out of mitochondria and cell)(diffuse out of mitochondria and cell)

Preparatory StepPreparatory Step

Cytoplasm

Matrix of the mitochondria

------------------------------------------------------------

Aerobic RespirationAerobic Respiration

For each glucose metabolized the For each glucose metabolized the Preparatory Step makesPreparatory Step makes

• 2 NADH - go to ETS2 NADH - go to ETS

• 2 CO2 CO2 2 - diffuse out of mitochondria and cell- diffuse out of mitochondria and cell

• 2 Acetyl Co-A - enter into Krebs* cycle2 Acetyl Co-A - enter into Krebs* cycle

*aka - citric acid cycle*aka - citric acid cycle

Preparatory Step SummaryPreparatory Step Summary

Where and when it occurs:Where and when it occurs: Substrate:Substrate: End Product:End Product: Also made:Also made:

______________________ ______________________

Preparatory Step SummaryPreparatory Step Summary

Where and when it occurs: Where and when it occurs: Occurs as pyruvate Occurs as pyruvate enter mitochondria, occurs under aerobic enter mitochondria, occurs under aerobic conditionsconditions

Substrate: Substrate: 2 Pyruvate (3C)2 Pyruvate (3C)End Product: End Product: 2 Acetyl-CoA (2C)2 Acetyl-CoA (2C)

Also made:Also made: 2 CO2 CO22

2 NADH2 NADH

Citric Acid Cycle = Krebs CycleCitric Acid Cycle = Krebs Cycle

Step 1: Each Acetyl-CoA (2C) joins with Step 1: Each Acetyl-CoA (2C) joins with an oxaloacetate (4C) to form a citrate an oxaloacetate (4C) to form a citrate (6C)(6C)

Rest of Krebs cycle reactions occurRest of Krebs cycle reactions occur• Last reaction produces another Last reaction produces another

oxaloacetate (4C) which joins with the oxaloacetate (4C) which joins with the next available acetyl-co A…….next available acetyl-co A…….

• ATP, NADH, FADHATP, NADH, FADH22, and CO, and CO22 are are made in these reactions….made in these reactions….see boardsee board

Acetyl CoA

CoA

CoA

Oxaloacetate

CITRIC ACID CYCLE

Citrate

2 carbons enter cycle

leavescycle

Alpha-ketoglutarate

leavescycle

CO2

NAD

NADH H

ADP

ATP

P

CO2

NADH H NAD

NADH

NAD

H

Malate

FADH2

FAD

Succinate

In the Krebs cycle, the metabolism of In the Krebs cycle, the metabolism of 2 pyruvates made from a single 2 pyruvates made from a single glucose produces:glucose produces: 2 ATP - 2 ATP - by substrate-level phosphorylationby substrate-level phosphorylation 6 NADH 6 NADH - go to ETS- go to ETS 2 FADH2 FADH22 - go to ETS- go to ETS

4 CO4 CO22 - diffuse out of mitochondria and cell- diffuse out of mitochondria and cell

Krebs Cycle SummaryKrebs Cycle Summary

Where it occurs:Where it occurs: Starting substrates:Starting substrates: Last product of pathway:Last product of pathway: Also made Also made (in total for 2 acetyl-CoA entering)(in total for 2 acetyl-CoA entering)

____ CO____ CO22

____ ATP ____ ATP (method made by?)(method made by?)

____ NADH____ NADH

____ FADH____ FADH22

Krebs Cycle SummaryKrebs Cycle Summary

Where it occurs: Where it occurs: matrix of mitochondriamatrix of mitochondria Starting substrates: Starting substrates: acetyl-CoA, oxaloacetateacetyl-CoA, oxaloacetate Last product of pathway: Last product of pathway: oxaloacetateoxaloacetate Also made Also made (in total for 2 acetyl-CoA)(in total for 2 acetyl-CoA)

4 CO4 CO22

2 ATP (by substrate level phophorylation)2 ATP (by substrate level phophorylation)

6 NADH6 NADH

2 FADH2 FADH22

Electron Transport Electron Transport ChainChain

ETC occurs at ETC occurs at electron carrierselectron carriers (proteins) (proteins) located on the inner membrane of the located on the inner membrane of the mitochondriamitochondria Electrons from NADH and FADHElectrons from NADH and FADH2 2 are passed are passed

from one electron carrier to the next.from one electron carrier to the next.

• Transfers are called red-ox reactionsTransfers are called red-ox reactions

• Each transfer releases energy Each transfer releases energy

Electron Transport Chain (ETC)Electron Transport Chain (ETC)

Some of the electron carriers are also Some of the electron carriers are also proton (Hproton (H++) pumps) pumps

• Use the energy released by the red-ox Use the energy released by the red-ox reactions (e transfer reactions) to pump Hreactions (e transfer reactions) to pump H++ out of the matrix.out of the matrix.

Intermembranespace

Innermitochondrialmembrane

Mitochondrialmatrix

Proteincomplex Electron

carrier

Electronflow

NADH NAD

FADFADH2

H

H

HH

H2O

H

H

ATPsynthase

2O212

H

PADP ATP

Electron Transport Chain Chemiosmosis

HH

HH

HH

HH

HH

HH

HH

ETSETS

NADH and FADHNADH and FADH22 each transfer each transfer 2e and H2e and H++

to a specific ETC proteinto a specific ETC protein Notice -- they do NOT start with the same Notice -- they do NOT start with the same

ETC proteinETC protein

In the process are the NADH and In the process are the NADH and FADHFADH22 oxidized or reduced? oxidized or reduced?

Intermembranespace

Innermitochondrialmembrane

Mitochondrialmatrix

Proteincomplex Electron

carrier

Electronflow

NADH NAD

FADFADH2

H

H

HH

H2O

H

H

ATPsynthase

2O212

H

PADP ATP

Electron Transport Chain Chemiosmosis

HH

HH

HH

HH

HH

HH

HH

ETCETC

HH+ + from the matrixfrom the matrix follow the electrons into follow the electrons into proton pumpsproton pumps

At each proton pump the HAt each proton pump the H++ are pumped are pumped out of the matrix into the intermembrane out of the matrix into the intermembrane spacespace

ETSETS

This creates an electrical & chemical This creates an electrical & chemical gradientgradient Form of _________ energyForm of _________ energy

ETC – Final Electron AcceptorETC – Final Electron Acceptor

Electron transfers stop when the last ETC Electron transfers stop when the last ETC protein transfers the 2e to oxygen which:protein transfers the 2e to oxygen which: Joins with HJoins with H++ to form water to form water

The last electron acceptor is oxygen and The last electron acceptor is oxygen and water forms. (know this)water forms. (know this)

Chemiosmosis and ATP SynthesisChemiosmosis and ATP Synthesis

…….back to the H.back to the H++ ions pumped into the ions pumped into the intermembrane spaceintermembrane space

The potential energy of HThe potential energy of H++ gradient is gradient is drive ATP synthesis at the enzyme ATP drive ATP synthesis at the enzyme ATP synthasesynthase

ETC and ATP SynthesisETC and ATP Synthesis

The enzyme ATP synthase is embedded The enzyme ATP synthase is embedded in the inner membrane of the mitochondriain the inner membrane of the mitochondria

The flow of HThe flow of H++ through this enzyme through this enzyme releases energy and this energy is used to releases energy and this energy is used to make ATP .make ATP .

ETCETC


This method of making ATP is calledThis method of making ATP is called Oxidative phosphorylationOxidative phosphorylation Also referred to as Also referred to as chemiosmosischemiosmosis


The more HThe more H++ pumped out of the matrix pumped out of the matrix The steeper the gradientThe steeper the gradient the more potential energythe more potential energy the more ATP that can be made by ATP the more ATP that can be made by ATP

synthasesynthase

ETC and ATP SynthesisETC and ATP Synthesis

Each Each NADHNADH made in the mito. results in made in the mito. results in enough Henough H++ being pumped out of the matrix being pumped out of the matrix to make to make 3 ATP3 ATP..

Each Each FADHFADH22 results in enough H results in enough H++ being being

pumped out of the matrix to make pumped out of the matrix to make 2 ATP2 ATP..

NADH from GlycolysisNADH from Glycolysis

The NADH made in glycolysis must enter The NADH made in glycolysis must enter the matrix in order to deliver their electrons the matrix in order to deliver their electrons to the ETCto the ETC

How they “enter” the mitochondria How they “enter” the mitochondria depends upon the cell type. depends upon the cell type.


In most cells the 2 NADH made in In most cells the 2 NADH made in glycolysis pass their electrons and Hglycolysis pass their electrons and H++ to to FADFAD in the matrix making:in the matrix making: 2 FADH2 FADH2 2 -- take the electrons and H-- take the electrons and H+ + to the to the

ETC where a total of ____ ATP are madeETC where a total of ____ ATP are made


In liver, heart, and kidney cells the 2 In liver, heart, and kidney cells the 2 NADH made in the cytoplasm pass their NADH made in the cytoplasm pass their electrons and Helectrons and H++ to NAD to NAD+ + in the matrix in the matrix making:making: 2 NADH2 NADH -- which take the electrons and H-- which take the electrons and H+ + to to

the ETC where a total of ____ ATP are madethe ETC where a total of ____ ATP are made

or 2 NADH

ATP Synthesis SummaryATP Synthesis Summary

GlycolysisGlycolysis ____ ATP (net) (method?)____ ATP (net) (method?) ____ NADH ____ NADH ____ ATP ____ ATP (most cells)(most cells)

Preparatory stepPreparatory step ____ ATP____ ATP _____ NADH _____ NADH ____ ATP (method?) ____ ATP (method?)

ATP Synthesis SummaryATP Synthesis Summary

Krebs CycleKrebs Cycle____ ATP ____ ATP (method?)(method?)

____ NADH ____ NADH ____ ATP ____ ATP (method?)(method?)

____ FADH____ FADH22 ____ ATP ____ ATP (method?)(method?)

NADH and FADHNADH and FADH2 2 SummarySummary

Glycolysis Glycolysis 2 NADH 2 NADH • Made in the cytoplasmMade in the cytoplasm• How they enter the mitochondria depends upon How they enter the mitochondria depends upon

the type of cellthe type of cell

Preparatory Step Preparatory Step 2 NADH 2 NADH

Kreb’s Cycle Kreb’s Cycle 6 NADH and 2 FADH 6 NADH and 2 FADH22

FermentationFermentation

Under Under anaerobic conditionsanaerobic conditions the products the products of glycolysis enter fermentation reactions.of glycolysis enter fermentation reactions.

All fermentation reactions occur in the All fermentation reactions occur in the cytoplasm.cytoplasm.


The purpose of all types of fermentation is The purpose of all types of fermentation is to regenerate NADto regenerate NAD++ so that glycolysis can so that glycolysis can continue.continue.


Cell’s have a limited supply of NAD Cell’s have a limited supply of NAD ++

The cell’s major source of NADThe cell’s major source of NAD++ is the first is the first step of the ETCstep of the ETC

Under anaerobic conditions the Krebs cycle Under anaerobic conditions the Krebs cycle and ETC stopand ETC stop• As a result NADAs a result NAD++ is no longer made in the is no longer made in the

mitochondria.mitochondria.


The two most common forms of The two most common forms of fermentation are:fermentation are: Lacate fermentationLacate fermentation Alcoholic fermentation Alcoholic fermentation

Which type of fermentation occurs Which type of fermentation occurs depends upon the organism.depends upon the organism.

Lactate FermentationLactate Fermentation

Lactate fermentation occurs in:Lactate fermentation occurs in: Humans and all other animalsHumans and all other animals Many bacteriaMany bacteria

Lactate FermentationLactate Fermentation

2 Pyruvate* (3C)2 Pyruvate* (3C)

2 Lactate* (3C)2 Lactate* (3C)

* Also called: pyruvic acid and lactic acid* Also called: pyruvic acid and lactic acid

2 NADH

2 NAD+ reused in glycolysis

Lactate build up in the cell results in:Lactate build up in the cell results in:

Increased blood supply to the areaIncreased blood supply to the area Blood brings oxygenBlood brings oxygen Blood “washes” out the lactateBlood “washes” out the lactate Lactate is taken to the liver where it is Lactate is taken to the liver where it is

converted back to pyruvate (called the Cori converted back to pyruvate (called the Cori cycle)cycle)• Too much lactate in the blood can cause acidosisToo much lactate in the blood can cause acidosis

If the lactate levels get too high cramping If the lactate levels get too high cramping occurs - painfuloccurs - painful

Alcoholic FermentationAlcoholic Fermentation

Alcoholic fermentation occurs in:Alcoholic fermentation occurs in: Yeast (a fungus)Yeast (a fungus)

• used in making alcoholic beverages and “yeast” used in making alcoholic beverages and “yeast” breadsbreads

Many bacteriaMany bacteria• Including those used to make Swiss cheeseIncluding those used to make Swiss cheese


2 Pyruvate (3C)2 Pyruvate (3C)

2 Acetaldehyde (2C)2 Acetaldehyde (2C)

2 Ethanol (2C)2 Ethanol (2C)

__________

2 NADH

2 NAD+ - reused in glycolysis


Ethanol (alcohol) builds up in the cell Ethanol (alcohol) builds up in the cell When it reaches too high a level it When it reaches too high a level it

denatures the cell’s proteins.denatures the cell’s proteins. This results in cell death!This results in cell death!

Wild yeasts die at 4% alcohol, wine making Wild yeasts die at 4% alcohol, wine making yeasts die at 14% alcohol.yeasts die at 14% alcohol.


Reactions cannot be reversed.Reactions cannot be reversed. Remember, the lactate fermentation reaction Remember, the lactate fermentation reaction

is reversible is reversible • Lactate can be converted back to pyruvate in the Lactate can be converted back to pyruvate in the

liver, not in the cell it’s made in liver, not in the cell it’s made in

This is the end of the slides needed.This is the end of the slides needed. The slides that follow are slides that give The slides that follow are slides that give

an overview of concepts related to the an overview of concepts related to the ETC. ETC.

Electron Transfers and EnergyElectron Transfers and Energy

Electron transfer reactions are called Electron transfer reactions are called oxidation reduction reactionsoxidation reduction reactions Oxidation – loss of electron(s)Oxidation – loss of electron(s) Reduction – gain of electron(s)Reduction – gain of electron(s) HH++ often follow the electrons often follow the electrons


ALL cells use the transfer of electrons and ALL cells use the transfer of electrons and HH++ to capture some of the energy stored in to capture some of the energy stored in chemical bondschemical bonds Energy is temporarily stored in NADH and Energy is temporarily stored in NADH and

FADHFADH22

• The stored energy is then used to make ATPThe stored energy is then used to make ATP


NADNAD++ + H + H + + + + 2 e2 e NADH NADH FAD + 2 HFAD + 2 H++ + + 2 e2 e FADH FADH22

Is the NADIs the NAD++ oxidized or reduced in this oxidized or reduced in this reaction?reaction?

In general the reduced molecule is of greater In general the reduced molecule is of greater energy due to the added energy of the energy due to the added energy of the electronselectrons

Electron Transfer ChainsElectron Transfer Chains

In mitochondria and chloroplasts there are In mitochondria and chloroplasts there are electron transfer chains embedded in the electron transfer chains embedded in the inner membranes inner membranes The passage of the electrons from electron The passage of the electrons from electron

transfer protein to protein results in creation of transfer protein to protein results in creation of an electrochemical gradientan electrochemical gradient

This gradient is a form of stored energy and This gradient is a form of stored energy and can be used to make ATPcan be used to make ATP


In mitochondria:In mitochondria: NADH and FADHNADH and FADH22 give electrons and H give electrons and H++ to to

specific proteins on the inner membrane of specific proteins on the inner membrane of the mitochondriathe mitochondria• this releases their stored energythis releases their stored energy

H H ++ follow the electrons into the proteins follow the electrons into the proteins


Energy given off by the electron transfers is Energy given off by the electron transfers is used to pump Hused to pump H+ + across the inner membrane across the inner membrane into the outer compartmentinto the outer compartment

This creates a chemical/electrical gradientThis creates a chemical/electrical gradient• A form of potential energy A form of potential energy • An ATP-synthesizing enzyme uses this energy to An ATP-synthesizing enzyme uses this energy to

make ATPmake ATP

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How Cells Harvest Chemical Energy. ATP Is Universal Energy Source Photosynthesizers get energy from the sun Consumers get energy from plants or other