how cells harvest chemical energy. atp is universal energy source photosynthesizers get energy from...
TRANSCRIPT
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
GlycolysisGlycolysis
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
GlycolysisGlycolysis
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?
GlycolysisGlycolysis
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?)
Glycolysis SummaryGlycolysis Summary
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)
Glycolysis SummaryGlycolysis Summary
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
GLYCOLYSISGLYCOLYSIS
ANAEROBIC • Fermentation occurs• Type depends upon cell type
AEROBIC RESPIRATION• Preparatory step• Krebs Cycle• Electron Transport System
OR
GLYCOLYSISGLYCOLYSIS
ANAEROBIC
ReactionsOccur in Cytoplasm
AEROBIC RESPIRATION
ReactionsOccur in Mitochondria
OR
GLYCOLYSISGLYCOLYSIS
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
Chemiosmosis and ATP SynthesisChemiosmosis and ATP Synthesis
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
Chemiosmosis and ATP SynthesisChemiosmosis and ATP Synthesis
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.
NADH from GlycolysisNADH from Glycolysis
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
NADH from GlycolysisNADH from Glycolysis
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.
FermentationFermentation
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.
FermentationFermentation
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.
FermentationFermentation
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
Alcoholic FermentationAlcoholic Fermentation
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
Alcoholic FermentationAlcoholic Fermentation
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.
Alcoholic FermentationAlcoholic Fermentation
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
Electron Transfers and EnergyElectron Transfers and Energy
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
Electron Transfers and EnergyElectron Transfers and Energy
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
Electron Transfer ChainsElectron Transfer Chains
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
Electron Transfer ChainsElectron Transfer Chains
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