MİCROBİAL METABOLİSMMİCROBİAL METABOLİSM

METABOLISMMETABOLISM is defined as the sum is defined as the sum of all chemical reactions occurring of all chemical reactions occurring

within a living organism. within a living organism.

Metabolism = Anabolism + Metabolism = Anabolism + CatabolismCatabolism

MetabolismMetabolism

CatabolismCatabolism

The breakdown of complex organic The breakdown of complex organic molecules into simpler molecules molecules into simpler molecules usually by hydrolysisusually by hydrolysis

Generally hydrolyticGenerally hydrolytic Exergonic, energy releasing Exergonic, energy releasing

(produce energy)-energy stored in (produce energy)-energy stored in chemical bonds is released.chemical bonds is released.

The chemical processes of The chemical processes of digestion typically occur by this digestion typically occur by this route.route.

AnabolismAnabolism The synthesis of complex organic molecules The synthesis of complex organic molecules

from simpler molecules usually by condensationfrom simpler molecules usually by condensation Generally dehydration synthesis reactions Generally dehydration synthesis reactions

(release water)(release water) Endergonic, energy-requiring (consume energy)Endergonic, energy-requiring (consume energy) The energy for anabolic reactions is provided by The energy for anabolic reactions is provided by

catabolic reactions; they are ALWAYS LINKED.catabolic reactions; they are ALWAYS LINKED. Energy is ultimately stored in the form of the Energy is ultimately stored in the form of the

energy -rich molecule, ATPenergy -rich molecule, ATP..

Energy Classes of MicrobesEnergy Classes of Microbes

Microbes nedd three things to grow Energy source Nutrients Suitable environmental conditions

Carbon sourceCarbon source– Heterotrophy: biomass generated from Heterotrophy: biomass generated from

organic carbonorganic carbon– Autotrophy: biomass generated from Autotrophy: biomass generated from

CO2CO2 Energy source

– Phototroph (light)– Chemotroph(chemicals)

Chemoorganotroph(gain energy from breaking organic chemical bonds)

Chemolithoautotroph(gain energy from breaking inorganic chemical bonds)

Autotrophs:is an organism that Autotrophs:is an organism that produces complex organic produces complex organic compounds from simple inorganic compounds from simple inorganic molecules using energy from light molecules using energy from light or inorganic chemical reactionsor inorganic chemical reactions..

Heterotrophs(Organotrophs):OrgaHeterotrophs(Organotrophs):Organic compounds serve both as nic compounds serve both as energy source and carbon source.energy source and carbon source.

PhotoautotrophsPhotoautotrophs or or PhototrophPhototroph : : Phototrophs are organisms (commonly Phototrophs are organisms (commonly plants) that carry out photosynthesis to plants) that carry out photosynthesis to acquire energyacquire energy

Chemotroph: Chemotrophs are Chemotroph: Chemotrophs are organisms that obtain energy by the organisms that obtain energy by the oxidation of electron donating molecules oxidation of electron donating molecules in their environments. These molecules in their environments. These molecules can be organic (organotrophs) or can be organic (organotrophs) or inorganic (lithotrophs; such as NHinorganic (lithotrophs; such as NH44, NO, NO22, , HH22S, FeS, Fe22 or H or H22 ). ).

PhotoheterotrophsPhotoheterotrophs (or (or photoorganotrophsphotoorganotrophs))

organisms which use light for organisms which use light for energy, but cannot use carbon energy, but cannot use carbon dioxide as their sole carbon dioxide as their sole carbon source. They use compounds such source. They use compounds such as carbohydrates, fatty acids and as carbohydrates, fatty acids and alcohols as their organic "food“.alcohols as their organic "food“.

ChemoheterotrophChemoheterotroph::

Most chemoheterotrophs derive Most chemoheterotrophs derive energy from organic molecules likeenergy from organic molecules like glucose.glucose.

HIGH ENERGY HIGH ENERGY COMPOUNDSCOMPOUNDS

ATP is the energy currency of the cellATP is the energy currency of the cell High energy released when High energy released when phosphate is hydrolized phosphate is hydrolized (ATD,ADP,AMP)(ATD,ADP,AMP)Acetyl phosphate Acetyl phosphate Acetyl coenzyme AAcetyl coenzyme APhospho-enol pyruvatePhospho-enol pyruvate

Energy is conserved in the Energy is conserved in the form of phosphate bondsform of phosphate bonds

Energy is stored in ATPEnergy is stored in ATP

ROLE OF ATP İN ROLE OF ATP İN METABOLİZMMETABOLİZM

ATP (adenosine triphosphate) ATP (adenosine triphosphate) stores the energystores the energy generated generated by catabolic reactions and by catabolic reactions and makes itmakes it available for anabolic available for anabolic reactionsreactions

ATP generated in exergonic ATP generated in exergonic reactions and use to drive reactions and use to drive endergonic reactionsendergonic reactions

HOW İS ATP GENARETE?HOW İS ATP GENARETE? Substrate-level Substrate-level

phosphorylation is phosphorylation is the production of the production of ATP from ADP by a ATP from ADP by a direct transfer of a direct transfer of a high-energy high-energy phosphate group phosphate group from a from a phosphorylated phosphorylated intermediate intermediate metabolic metabolic compound in an compound in an exergonic catabolic exergonic catabolic pathway pathway

II. Electron-transport II. Electron-transport phosphorylationphosphorylation: : Membrane-Membrane-associatedassociated mechanism where mechanism where ATP formation is ATP formation is coupled withcoupled withflow of electrons flow of electrons from donor to from donor to acceptor. Occursacceptor. Occursin respiratory in respiratory chain and in chain and in photosynthetic photosynthetic reaction reaction sequences.sequences.

EnergeticsEnergetics Energetics Energetics  Gibbs Free-Energy (G) Gibbs Free-Energy (G) ReactionReaction has a free-energy change has a free-energy change

– Negative: exergonic Negative: exergonic – Positive: endergonic Positive: endergonic – Zero: equilibrium Zero: equilibrium

Standard concentrations—tables of Standard concentrations—tables of ΔGf°’ ΔGf°’

Calculation of Calculation of reactionreaction energetics  energetics  First, must write balanced equation First, must write balanced equation

– E.g., 2H2 + O2 → 2H2O E.g., 2H2 + O2 → 2H2O Calculation of ΔG°’ for a Calculation of ΔG°’ for a reactionreaction

– ΔG°’ = ΔGf°’products - ΔGf°’reactants ΔG°’ = ΔGf°’products - ΔGf°’reactants – ΔG°’ = 2 x (-237.2 kJ/mol) – (2 x 0 + 0) ΔG°’ = 2 x (-237.2 kJ/mol) – (2 x 0 + 0)

Calculation of ΔG for a Calculation of ΔG for a reactionreaction – ΔG = ΔG°’ + RT x ln(k) ΔG = ΔG°’ + RT x ln(k)

Energy is defined as the ability to Energy is defined as the ability to do work.do work.

Chemical energy is the energy Chemical energy is the energy released when organic or inorganic released when organic or inorganic compounds are oxidized.compounds are oxidized.

Chemical energy is derived from Chemical energy is derived from the energy stored in chemical the energy stored in chemical bonds. When bonds are made or bonds. When bonds are made or broken there is a quantifiable broken there is a quantifiable amount of energy expended.amount of energy expended.

FREE ENERGYFREE ENERGY The energy (i.e., the work needed to The energy (i.e., the work needed to

transport ions against a transport ions against a concentration gradient) comes from concentration gradient) comes from the internal energy that is released the internal energy that is released during the rxn.during the rxn.

The energy The energy availableavailable to do work is to do work is free energy free energy (ΔG) (ΔG)

if if G is negative, reaction is G is negative, reaction is spontaneous and energy yieldingspontaneous and energy yielding = = exergonicexergonic

if if G is positive, reaction is non-G is positive, reaction is non-spontaneous and energy requiring spontaneous and energy requiring

= = endergonicendergonic

Summary of Redox and eSummary of Redox and e- -

Carriers,Carriers,Reduction and Reduction and OxidationOxidation

Redox reactionsRedox reactions

Oxidation - Reduction,Oxidation - Reduction,

Oxidant – Reductant, Oxidant – Reductant,

Reduction potential EReduction potential E00, ,

Half reactions, Half reactions,

Use of the Electron TowerUse of the Electron Towerss

All organisms obtain energy by transferring All organisms obtain energy by transferring electrons from an electrons from an electron donorelectron donor to an to an electron acceptor.electron acceptor.

Electron acceptor Electron acceptor gains electrons gains electrons ReducedReduced

Electron donor Electron donor gives up electrons gives up electrons OxidizedOxidized

Electron donor understood as energy Electron donor understood as energy source, but it’s the reaction that generates source, but it’s the reaction that generates energyenergy

The generally accepted convention is keep The generally accepted convention is keep the electrons on the left side of the reactionthe electrons on the left side of the reaction

Electrons are transferred by oxidation-Electrons are transferred by oxidation-reduction reactions reduction reactions (redox).(redox).

a) a) An atom becomes more reduced when An atom becomes more reduced when it undergoes a chemical reaction in it undergoes a chemical reaction in

which itwhich it

Gains electronsGains electrons

By bonding to a less By bonding to a less electronegative atomelectronegative atom

And often this occurs when the And often this occurs when the atom becomes bonded to a atom becomes bonded to a

hydrogenhydrogen

Oxidant + eOxidant + e-- reduced form reduced form

b) b) An atom becomes more An atom becomes more oxidized when it undergoes a oxidized when it undergoes a chemical reaction in which itchemical reaction in which it

Loses electronsLoses electronsBy bonding to a more By bonding to a more electronegative atomelectronegative atom

And often this occurs when the And often this occurs when the atom becomes bonded to an atom becomes bonded to an

oxygenoxygen

Reductant – eReductant – e-- oxidized form oxidized form

c)c) In metabolic pathways, we are In metabolic pathways, we are often concerned with the oxidation often concerned with the oxidation or reduction of carbon. or reduction of carbon.

d)d) Reduced forms of carbon (e.g. Reduced forms of carbon (e.g. hydrocarbons, methane, fats, hydrocarbons, methane, fats, carbohydrates, alcohols) carry a carbohydrates, alcohols) carry a great deal of potential chemical great deal of potential chemical energy stored in their bonds.energy stored in their bonds.

e)e) Oxidized forms of carbon (e.g. Oxidized forms of carbon (e.g. ketones, aldehydes, carboxylic ketones, aldehydes, carboxylic acids, carbon dioxide) carry very acids, carbon dioxide) carry very little potential chemical energy in little potential chemical energy in their bonds.their bonds.

REDUCEDREDUCED OXIDIZED OXIDIZEDOXIDIZED OXIDIZED REDUCEDREDUCED

AHAH22 + B → A + BH + B → A + BH22

AHAH22 - dehydrogenation, i.e., the - dehydrogenation, i.e., the ELECTRON DONORELECTRON DONOR

B - the ELECTRON ACCEPTOR in B - the ELECTRON ACCEPTOR in respiration is “external” and may be respiration is “external” and may be O2 orO2 or

an oxidized form of N, S, C, Fe, Mn, etc. an oxidized form of N, S, C, Fe, Mn, etc. In fermentation, the electron In fermentation, the electron

acceptor isacceptor is

““internal” and is often an organic internal” and is often an organic compoundcompound

No free electrons are present. No free electrons are present. The reactions must be added to make The reactions must be added to make

a complete reaction.a complete reaction. The generally accepted convention is The generally accepted convention is

keep the electrons on the left side of keep the electrons on the left side of the reaction. the reaction.

Reduction and oxidation always occur Reduction and oxidation always occur together. together.

All redox reactions are coupled half All redox reactions are coupled half reactions.reactions.

Amount of energy generated is based Amount of energy generated is based on the nature of both the electron on the nature of both the electron donor and electron acceptor (drop in donor and electron acceptor (drop in tower)tower)

Half ReactionsHalf Reactions Often split redox reactions in two:Often split redox reactions in two:

– oxidation half rxn oxidation half rxn e- leaves left, goes right e- leaves left, goes right FeFe2+2+ Fe Fe3+3+ + e- + e-

– Reduction half rxn Reduction half rxn e- leaves left, goes right e- leaves left, goes right OO22 + 4 e + 4 e-- 2 H 2 H22OO

SUM of the half reactions yields the total SUM of the half reactions yields the total redox reactionredox reaction

4 Fe4 Fe2+2+ 4 Fe 4 Fe3+3+ + 4 e- + 4 e-

OO22 + 4 e + 4 e-- 2 H 2 H22OO

4 Fe4 Fe2+2+ + O + O22 4 Fe 4 Fe3+3+ + 2 H + 2 H22OO

POTENTIAL ENERGY (EPOTENTIAL ENERGY (E00))

The reduction potentialThe reduction potential

Electron TowerElectron Tower Oxidation / Reduction Oxidation / Reduction

PairsPairs first in pair is oxidizer first in pair is oxidizer

(accepts e-)(accepts e-) second in pair is reduced second in pair is reduced

(donates e-)(donates e-) Due to energy required Due to energy required

to build molecules, strong to build molecules, strong e- donors are found at the e- donors are found at the top of tower, while strong top of tower, while strong e- acceptors are found at e- acceptors are found at the bottom of tower.the bottom of tower.

As electrons are donated As electrons are donated from the top of the from the top of the tower , they can be tower , they can be caught by acceptors at caught by acceptors at various levels. The farther various levels. The farther the electron fall before the electron fall before they are caught, the they are caught, the greater the difference in greater the difference in reduction potential reduction potential between e- donor and e- between e- donor and e- acceptor and the more acceptor and the more energy released.energy released.

To determine which direction To determine which direction the reactions go, see which is the reactions go, see which is “higher”“higher”

on the e- toweron the e- tower

ELECTRON CARRIERSELECTRON CARRIERSReduction/oxidation is mediated Reduction/oxidation is mediated by by

electron carriers in the cellelectron carriers in the cell

• • Electron carriers can be Electron carriers can be divided into those that are divided into those that are freely diffusable and those that freely diffusable and those that are fixedare fixed

• • Fixed = cytochromes Fixed = cytochromes associated with the cytoplasmic associated with the cytoplasmic membrane membrane

• • Freely diffusable =NAD(H) or Freely diffusable =NAD(H) or

NADP(H) found in the cytoplasmNADP(H) found in the cytoplasm

These are electron plus proton These are electron plus proton carriers transporting 2e-carriers transporting 2e- and 2H+ and 2H+ at a time (-0.32V)at a time (-0.32V)

NAD is used in energy generation NAD is used in energy generation (catabolic reactions). NADP is (catabolic reactions). NADP is

used in biosynthetic reactions used in biosynthetic reactions (anabolic)(anabolic)

NAD and NADP are coenzymes NAD and NADP are coenzymes that are recycledthat are recycled

Microbes, e- flowMicrobes, e- flow Catabolism – breakdown Catabolism – breakdown

of any compound for of any compound for energyenergy

Anabolism – Anabolism – consumption of that consumption of that energy for biosynthesisenergy for biosynthesis

Transfer of e- facilitated Transfer of e- facilitated by e- carriers, some by e- carriers, some bound to the membrane, bound to the membrane, some freely diffusiblesome freely diffusible

3.3. Enzymatic Pathways for MetabolismEnzymatic Pathways for Metabolism– Metabolic reactions take place in a Metabolic reactions take place in a

step-wise fashion in which the step-wise fashion in which the atoms of the raw materials are atoms of the raw materials are rearranged, often one at a time, rearranged, often one at a time, until the formation of the final until the formation of the final product takes place.product takes place.

– Each step requires its own Each step requires its own enzyme.enzyme.

– The sequence of enzymatically-The sequence of enzymatically-catalyzed steps from a starting catalyzed steps from a starting raw material to final end products raw material to final end products is called an enzymatic pathway (or is called an enzymatic pathway (or metabolic pathway)metabolic pathway)

Membrane bound electron Membrane bound electron carrierscarriers

Membrane bound electron Membrane bound electron carriers have 2 basic functions: carriers have 2 basic functions:

1) Accept electrons and 1) Accept electrons and transfer themtransfer them

2) Conserve energy released 2) Conserve energy released for synthesis of ATPfor synthesis of ATP

Enzymes involved in oxidation Enzymes involved in oxidation reduction reactions:reduction reactions:

NADH dehydrogenaseNADH dehydrogenase Flavoproteins (FMN & FAD) Flavoproteins (FMN & FAD) Iron-sulphur proteinsIron-sulphur proteins Cytochromes (heme) iron Cytochromes (heme) iron Lipid soluble quinonesLipid soluble quinones

Cytochromes:Cytochromes:– Transport electrons ONLYTransport electrons ONLY– Different cytochromes have different Different cytochromes have different

reduction potentials (cyt a, cytreduction potentials (cyt a, cyt b, etc)b, etc)

Nonheme iron-sulfur proteinsNonheme iron-sulfur proteinsOnly carry electronsOnly carry electrons

QuinonesQuinones– Accepts bothAccepts both protons and electrons but only protons and electrons but only

donates the electronsdonates the electrons NADH dehydrogenaseNADH dehydrogenaseFound on cytoplasmic face of membrane Found on cytoplasmic face of membrane Accepts e- and H+Accepts e- and H+ Flavoproteins (FMN & FAD) Flavoproteins (FMN & FAD) Prosthetic group derived from vitamin Prosthetic group derived from vitamin

B2B2 Accepts e- and H+, but only transfers e-Accepts e- and H+, but only transfers e-

MODES OF ENERGY MODES OF ENERGY PRODUCTIONPRODUCTION

Microorganisms oxidize Microorganisms oxidize carbohydrates as their primary carbohydrates as their primary source of energysource of energy

Glucose - most common energy Glucose - most common energy sourcesource

Energy obtained from Glucose by:Energy obtained from Glucose by:– RespirationRespiration– FermentationFermentation

Cellular RespirationCellular Energy

•The Stages of Cellular Respiration Cellular respiration has two stages. •Glycolysis The first stage of cellular respiration is called glycolysis. •Aerobic and Anaerobic Respiration The second stage of cellular respiration is either aerobic respiration (in the presence of oxygen) or anaerobic respiration (in the absence of oxygen). A large amount of ATP is made during aerobic respiration. NAD+ is recycled during the anaerobic process of fermentation.

Aerobic Cellular RespirationAerobic Cellular Respiration

4 subpathways4 subpathways

1. Glycolysis1. Glycolysis 2. Transition Reaction2. Transition Reaction 3. Kreb’s Cycle3. Kreb’s Cycle 4. Electron Transport System4. Electron Transport System

1. Glycolysis 1. Glycolysis (splitting of sugar)(splitting of sugar)

Oxidation of Glucose into 2 Oxidation of Glucose into 2 molecules of Pyruvic acidmolecules of Pyruvic acid

Embden-Meyerhof PathwayEmbden-Meyerhof Pathway

End Products of Glycolysis:End Products of Glycolysis:– 2 Pyruvic acid2 Pyruvic acid

– 2 NADH2 NADH22

– 2 ATP2 ATP

2. Transition Reaction2. Transition Reaction

Connects Glycolysis to Krebs CycleConnects Glycolysis to Krebs Cycle

End Products:End Products:– 2 Acetyl CoEnzyme A2 Acetyl CoEnzyme A

– 2 CO2 CO22

– 2 NADH2 NADH22

3. Krebs Cycle 3. Krebs Cycle (Citric Acid (Citric Acid Cycle)Cycle)

Series of chemical reactions that Series of chemical reactions that begin and end with citric acidbegin and end with citric acid

Products:Products:– 2 ATP2 ATP

– 6 NADH6 NADH22

– 2 FADH2 FADH22

– 4 CO4 CO22

4. Electron Transport 4. Electron Transport SystemSystem

Occurs within the cell membrane Occurs within the cell membrane of Bacteriaof Bacteria

Chemiosomotic Model of MitchellChemiosomotic Model of Mitchell– 34 ATP34 ATP

Total ATP production for the complete Total ATP production for the complete oxidation of 1 molecule of glucose in oxidation of 1 molecule of glucose in Aerobic RespirationAerobic Respiration

ATPATP Glycolysis 2Glycolysis 2 Transition Reaction 0Transition Reaction 0 Krebs Cycle 2Krebs Cycle 2 E.T.S. 34E.T.S. 34

Total 38 ATPTotal 38 ATP

Anaerobic RespirationAnaerobic Respiration

Electrons released by oxidation are Electrons released by oxidation are passed down an E.T.S., but oxygen passed down an E.T.S., but oxygen is notis not the final electron acceptor the final electron acceptor

Nitrate (NONitrate (NO33-) ----> Nitrite (NO-) ----> Nitrite (NO22-)-)

Sulfate (SOSulfate (SO2244-) ----> Hydrogen -) ----> Hydrogen

Sulfide (HSulfide (H22S)S)

Carbonate (COCarbonate (CO2244-) -----> Methane (CH-) -----> Methane (CH44))

Aerobic respirationAerobic respiration • • Kreb’s cycleKreb’s cycle

Pyruvic acid COPyruvic acid CO22 + NADH + ATP + NADH + ATP + FADH+ FADH

• • Electron transport chain (ETC)Electron transport chain (ETC) – – Carrier molecules that Carrier molecules that

transport electrons resulting in a transport electrons resulting in a step wise release of energy that step wise release of energy that is used to for ATPis used to for ATP

– – Final electron acceptor is OFinal electron acceptor is O22 which forms Hwhich forms H22OO

Anaerobic RespirationAnaerobic Respiration

• • Final electron acceptor is an Final electron acceptor is an inorganic molecule other that inorganic molecule other that oxygenoxygen

– – Nitrate (NONitrate (NO33--) ) Nitrite (NO Nitrite (NO22

--))

– – Sulfate (SOSulfate (SO44-2-2)) Hydrogen sulfide Hydrogen sulfide

(H(H22S)S)

– – Carbonate (COCarbonate (CO33-2-2) ) Methane (CH Methane (CH44))

• • Less ATP than aerobicLess ATP than aerobic

– – All components of Kreb’s cycle and All components of Kreb’s cycle and ETC can’t function.ETC can’t function.

FermentationFermentation

• • Conversion of pyruvic acid to organicConversion of pyruvic acid to organic• ProductProduct

• • Does not require oxygenDoes not require oxygen

• • No part of Kreb’s cycle or ETC usedNo part of Kreb’s cycle or ETC used

Lactic Acid FermenationLactic Acid Fermenation

Alcohol FermentationAlcohol Fermentation Both the electron donor and acceptor Both the electron donor and acceptor

are organic compounds and ATP is are organic compounds and ATP is generated solely via substrate-level generated solely via substrate-level phosphorylation.phosphorylation.

Fermentation releases little energy (2 Fermentation releases little energy (2 ATP/molecule of glucose) and most of ATP/molecule of glucose) and most of it remains in fermentation products.it remains in fermentation products.

Differences between Resp. and Differences between Resp. and Ferment.Ferment.

• • Fermentation: redox reaction occurring with no Fermentation: redox reaction occurring with no exogenous terminal electron acceptorexogenous terminal electron acceptor • • Instead fermentation is coupled to reduction of a Instead fermentation is coupled to reduction of a compound generated from the initial substrate, no compound generated from the initial substrate, no external electron acceptor is suppliedexternal electron acceptor is supplied • • Respiration: redox reaction requiring an Respiration: redox reaction requiring an

exogenous exogenous electron acceptorelectron acceptor • • In aerobic respiration this is molecular oxygen In aerobic respiration this is molecular oxygen

(O2), in (O2), in anaerobic respiration the electron acceptor can anaerobic respiration the electron acceptor can

vary vary eg. Nitrate or nitrite (see electron tower) eg. Nitrate or nitrite (see electron tower)

Embden-Meyerhof pathway-Embden-Meyerhof pathway-

Two more ADP and 2 NAD+ Two more ADP and 2 NAD+ molecules are used to make two molecules are used to make two molecules of NADH and two more molecules of NADH and two more molecules of ATP. This step also molecules of ATP. This step also yields two pyruvate molecules. yields two pyruvate molecules. The pyruvate still have most of The pyruvate still have most of the original energy that was the original energy that was found in the original glucose found in the original glucose molecule and the point of the of molecule and the point of the of aerobic cellular respiration will aerobic cellular respiration will be to harvest as much of that be to harvest as much of that energy as possible! energy as possible!

Aerobic respiration happens in Aerobic respiration happens in 33 stages: stages:

Stage 1Stage 1 – – GlycolysisGlycolysis

glycolglycol ysisysis

glucose splittingglucose splitting

Stage 2 – Stage 2 – Breakdown of Breakdown of pyruvic acidpyruvic acid

The pyruvic acid made in glycolysis The pyruvic acid made in glycolysis (stage1)(stage1) still contains a lot of still contains a lot of energyenergy

It can only be broken down to It can only be broken down to release the rest of the energy in release the rest of the energy in the the presencepresence ofof oxygenoxygen..

Stage Stage 3 3 – – Oxidative Oxidative PhosphorylationPhosphorylation

Requires the Electron Transport Requires the Electron Transport Chain…Chain…

the Electron Transport Chain is a the Electron Transport Chain is a

collection of proteins, embedded in collection of proteins, embedded in the inner membrane, used to the inner membrane, used to transport the electrons from NADH transport the electrons from NADH and FADHand FADH22

Krebs CycleKrebs Cycle

Also called: Citric Acid CycleAlso called: Citric Acid Cycle or or Tricarboxylic Acid Cycle Tricarboxylic Acid Cycle

Function: Oxidize pyruvic acid to Function: Oxidize pyruvic acid to COCO22

Produce: 3NADH, 1FADHProduce: 3NADH, 1FADH2 2 and 1ATPand 1ATP

Location: Mitochondria matrixLocation: Mitochondria matrix

Formation of Acetyl CoA:Formation of Acetyl CoA:Acetyl CoA is formed when the Acetyl CoA is formed when the pyruvate , from glycolysis, pyruvate , from glycolysis, combines with Coenzyme A… combines with Coenzyme A… tthhis takes place in the matrix.is takes place in the matrix.

RequirementsRequirements for Krebs Cycle for Krebs Cycle Pyruvic acid (3C acid)Pyruvic acid (3C acid) Coenzyme ACoenzyme A 3 NAD3 NAD++

1 ADP1 ADP 1 FAD1 FAD Double this list for each Double this list for each

glucose.glucose.

ResultsResults

Produces most of the cell's Produces most of the cell's energy in the form of NADH energy in the form of NADH and FADHand FADH22… not ATP… not ATP

Does NOT require ODoes NOT require O22

FADH = 2 ATPFADH = 2 ATP

NADH = 3 ATPNADH = 3 ATP

Electron Transport SystemElectron Transport System

The electron transport system The electron transport system (ETS) is a chain of electron carriers (ETS) is a chain of electron carriers associated with the cytoplasmic associated with the cytoplasmic membrane in prokaryotes and membrane in prokaryotes and mitochondria in eukaryotes.mitochondria in eukaryotes.

This system transfers the energy This system transfers the energy stored in NADH and FADH into stored in NADH and FADH into ATP. The chain consists of electron ATP. The chain consists of electron carriers such as flavin carriers such as flavin mononucleotide (FMN), coenzyme mononucleotide (FMN), coenzyme Q, iron–sulfur proteins, and Q, iron–sulfur proteins, and cytochromes.cytochromes.

Comparison of aerobic and Comparison of aerobic and anaerobic respirationanaerobic respiration

Aerobic Aerobic respiratirespirati

onon

Anaerobic RespirationAnaerobic Respiration

in animalsin animals in plants and in plants and yeastyeast

Oxygen Oxygen required?required?

yesyes nono nono

Glycolysis Glycolysis occursoccurs

yesyes yesyes yesyes

ATP yieldATP yield 38ATP38ATP 2ATP2ATP 2ATP2ATP

Glucose Glucose completely completely broke down?broke down?

yesyes nono nono

End productsEnd products Carbon Carbon dioxide dioxide and waterand water

Lactic acidLactic acid Ethanol and Ethanol and carbon carbon dioxidedioxide