Cellular RespirationCellular RespirationPart 2Part 2

Producing ATP by Oxidative Producing ATP by Oxidative PhosphorylationPhosphorylation

Energy from Macromolecules Energy from Macromolecules

Releasing Energy From GlucoseReleasing Energy From GlucoseGlucose (6C)Glucose (6C)

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

2 X Acetyl-CoA (2C)2 X Acetyl-CoA (2C)

CytoplasmCytoplasm

MitochondrionMitochondrion

Citric Acid Citric Acid CycleCycle

ATPATPee-- Carriers Carriers

ee-- Carriers Carriers

ee-- Carriers Carriers

Electron Transport Chain

Electron Transport Chain

½ O½ O22

HH22OO

ATPATP

2 H2 H++

4 CO4 CO22

2 CO2 CO22

ATPATP

GlycolysisGlycolysis

EnergyReleased

ee--

ee--ee--

EnergyReleased

OO2 2 presentpresent

Locations of Cellular Respiration ComponentsLocations of Cellular Respiration Components

Matrix: Citric Acid Cycle Matrix: Citric Acid Cycle and Pyruvate Oxidationand Pyruvate Oxidation

MitochondrionMitochondrion

A CristaA CristaInnerInnerMembrane:Membrane:Has ATP Synthase Has ATP Synthase Electron Transport ChainElectron Transport Chain

IntermembraneIntermembraneCompartmentCompartment

HH++ accumulates accumulates

aabb

OuterOuterMembraneMembrane

Sequence of Sequence of Electron CarriersElectron Carriers

The poison cyanide prevents

transfer of electrons to

oxygen

NADH donates electrons to

Complex I(NADH

Dehydrogenase)

FADH2 donates electrons to

Complex II (Succinate

Dehydrogenase)

Cytochromes are electron

carriers with a heme prosthetic

group

Formation of Formation of HH++ Gradient Gradient

The poison arsenic prevents the buildup of the

H+ gradient

Protons are pumped from the

matrix into the intermembrane

space

Flow of protons through ATP

synthase powers ATP production

ATP SynthaseATP Synthase

H+ ions cause the rotor of ATP

synthase to spin

Sites in the catalytic knob are activated to

catalyze ATP production

The inner mitochondrial membrane is

impermeable to H+, which can

only pass through the ATP synthase

The internal rod also spins as a result of rotor

movement

Oxidative PhosphorylationOxidative Phosphorylation

• Production of ATP as a result of electron transfer Production of ATP as a result of electron transfer through carriers in the Electron Transport Chainthrough carriers in the Electron Transport Chain– Electrons pass through a set of membrane-associated Electrons pass through a set of membrane-associated

carriers by a series of redox reactionscarriers by a series of redox reactions– Energy from electron transport powers the active Energy from electron transport powers the active

transport of Htransport of H++ to the intermembrane compartment of the to the intermembrane compartment of the mitochondrion, building a concentration gradient mitochondrion, building a concentration gradient

– Chemiosmosis: Diffusion of hydrogen ions (HChemiosmosis: Diffusion of hydrogen ions (H++) through ) through the differentially permeable inner mitochondrial the differentially permeable inner mitochondrial membrane, resulting in ATP production membrane, resulting in ATP production

• HH+ + can only cross the membrane into the mitochondrial can only cross the membrane into the mitochondrial matrix through the pores of an ATP-synthesizing enzymematrix through the pores of an ATP-synthesizing enzyme

• Movement of HMovement of H++ through the enzyme provides energy for through the enzyme provides energy for ATP synthesisATP synthesis

FermentationFermentation

Glucose (6C)Glucose (6C)

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

2 X Acetyl-CoA (2C)2 X Acetyl-CoA (2C)

CytoplasmCytoplasm

MitochondrionMitochondrion

Citric Acid Citric Acid CycleCycle

ATPATPee-- Carriers Carriers

ee-- Carriers Carriers

ee-- Carriers Carriers4 CO4 CO22

2 CO2 CO22

ATPATP

GlycolysisGlycolysis

oxidized eoxidized e-- Carriers Carriers

FermentationFermentation 2 X Lactate (3C)2 X Lactate (3C)(in muscle)(in muscle)OO2 2 presentpresent

when Owhen O22 becomes available becomes availableXX OO2 2 absentabsent

Alcoholic and Lactic Acid Alcoholic and Lactic Acid FermentationFermentation

Muscle cellsMicroorganisms

YeastsSome Plants

Alcoholic Fermentation

Lactic Acid Fermentation

Energy From MacromoleculesEnergy From Macromolecules

Glucose (6C)Glucose (6C)

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

2 X Acetyl-CoA (2C)2 X Acetyl-CoA (2C)

Citric AcidCitric AcidCycleCycle

GlycolysisGlycolysis

MonosaccharidesMonosaccharides

PolysaccharidesPolysaccharides

DisaccharidesDisaccharides

GluconeogenesisGluconeogenesis

Energy From MacromoleculesEnergy From Macromolecules

Glucose (6C)Glucose (6C)

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

2 X Acetyl-CoA (2C)2 X Acetyl-CoA (2C)

TriglyceridesTriglycerides

Fatty Acids Fatty Acids multiples of 2C multiples of 2C

GlycerolGlycerol(~5%) (~5%)

Citric AcidCitric AcidCycleCycle

Glucose (6C)Glucose (6C)

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

GlycolysisGlycolysisGluconeogenesisGluconeogenesis

DAPDAP

Energy From MacromoleculesEnergy From Macromolecules

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

2 X Acetyl-CoA (2C)2 X Acetyl-CoA (2C)

ProteinsProteins

Other amino Other amino AcidsAcids

3C-amino 3C-amino acidsacids

Citric AcidCitric AcidCycleCycle

Glucose (6C)Glucose (6C)

GlycolysisGlycolysisGluconeogenesisGluconeogenesis

Anabolic InterconversionsAnabolic Interconversions

Glucose (6C)Glucose (6C)

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

2 X Acetyl-CoA (2C)2 X Acetyl-CoA (2C)

Citric AcidCitric AcidCycleCycle

GlycolysisGlycolysis

PolysaccharidesPolysaccharides

GluconeogenesisGluconeogenesis

Fatty AcidsFatty Acids

GlycerolGlycerol

Amino AcidsAmino Acids

TriglyceridesTriglycerides

ProteinsProteins

Regulation of Regulation of GlycolysisGlycolysis

• Phosphofructokinase is Phosphofructokinase is – allosterically inhibited allosterically inhibited

by ATPby ATP– allosterically activatedallosterically activated

by ADP or AMPby ADP or AMP– inhibited by citrateinhibited by citrate

Regulation of the Citric Acid CycleRegulation of the Citric Acid Cycle

• Isocitrate dehydrogenaseIsocitrate dehydrogenase– responds to negative responds to negative

feedback from NADHfeedback from NADHand H+ and ATPand H+ and ATP

– is activated by ADP and is activated by ADP and NAD+NAD+

Regulation of Regulation of Acetyl-CoAAcetyl-CoA

• Entering the Citric Acid Entering the Citric Acid Cycle Cycle – Citrate synthase (1)Citrate synthase (1)

is inhibited by ATP is inhibited by ATP or NADHor NADH

• Use in Fatty Acid Use in Fatty Acid SynthesisSynthesis– Fatty Acid synthase (2)Fatty Acid synthase (2)

is stimulated by Citrateis stimulated by Citrate

(1)

(2)