Transcript Slide 1

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Oxidation
Energy-rich
molecule
Enzyme
H
Product
Reduction
H
+H+
H
H
H
H
2e–
H+
H
NAD+
NAD+
NAD
H
NAD
NAD+
1. Enzymes that use NAD+
as a cofactor for oxidation
reactions bind NAD+ and the
substrate.
2. In an oxidation–reduction
reaction, 2 electrons and
a proton are transferred
to NAD+, forming NADH.
A second proton is
donated to the solution.
3. NADH diffuses away
and can then donate
electrons to other
molecules.
1
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Electrons from food
2e–
Energy released
for ATP synthesis
High energy
Low energy
1/ O
2 2
2H+
H2O
2
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Reduction
H+
2H
Oxidation
3
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PEP
P
Enzyme
Enzyme
P
P
– ADP
– ATP
Adenosine
4
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Outer
mitochondrial
membrane
Glycolysis
Glucose
NADH
ATP
Intermembrane
space
Pyruvate
Pyruvate
Oxidation
NADH
Mitochondrial
matrix
Acetyl-CoA
CO2
CO2
NADH
Krebs
Cycle
FADH2
e–
NAD+ FAD O2
ATP
H2O
e– Electron e–
Transport Chain
ATP
Inner
mitochondrial
membrane
Chemiosmosis
ATP Synthase
H+
5
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Glycolysis
ATP
NADH
Pyruvate Oxidation
Krebs
Cycle
Electron Transport Chain
Chemiosmosis
STEP A
Glycolysis begins
with the addition of
energy. Two highenergy phosphates
(P) from two
molecules of ATP
are added to the
6-carbon molecule
glucose, producing
a 6-carbon
molecule with two
phosphates.
Priming Reactions
6-carbon glucose
(Starting material)
ATP
ATP
ADP
P
ADP
P
Cleavage
6-carbon sugar diphosphate
P
3-carbon sugar
phosphate
P
3-carbon sugar
phosphate
Oxidation and ATP Formation
Pi
Pi
NAD+
NAD+
NADH
NADH
ADP
ADP
ATP
ATP
ADP
ADP
ATP
ATP
3-carbon
pyruvate
STEP B
Then, the 6-carbon
molecule with two
phosphates is split in
two, forming two
3-carbon sugar
phosphates.
STEPS C and D
An additional
Inorganic phosphate
( Pi ) is incorporated
into each 3-carbon
sugar phosphate. An
oxidation reaction
converts the two
sugar phosphates
into intermediates
that can transfer a
phosphate to ADP to
form ATP. The
oxidation reactions
also yield NADH
giving a net energy
yield of 2 ATP and 2
NADH.
3-carbon
pyruvate
6
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CH2OH
Glucose
Glycolysis: The Reactions
NADH
Glucose
Pyruvate Oxidation
Glucose 6-phosphate
2
Electron Transport Chain
Chemiosmosis
Phosphoglucose
isomerase
Fructose 6-phosphate
3
ATP
Phosphofructokinase
1. Phosphorylation of
glucose by ATP.
ADP
Fructose 1,6-bisphosphate
2–3. Rearrangement,
followed by a second
ATP phosphorylation.
7. Removal of high-energy
phosphate by two ADP
molecules produces two
ATP molecules and leaves
two 3PG molecules.
Dihydroxyacetone
phosphate
Glyceraldehyde 3phosphate (G3P)
6
NAD+
Pi
NAD+
Pi
NADH
NADH
Glyceraldehyde
3-phosphate
dehydrogenase
1,3-Bisphosphoglycerate
1,3-Bisphosphoglycerate
(BPG)
(BPG)
7
ADP
ATP
P
ATP
3-Phosphoglycerate
(3PG)
CH2
2-Phosphoglycerate
(2PG)
2-Phosphoglycerate
(2PG)
9
H2O
H2O
Enolase
Phosphoenolpyruvate Phosphoenolpyruvate
(PEP)
(PEP)
ADP
10
ADP
ATP
Pyruvate kinase
ATP
Pyruvate
Pyruvate
P
O
O
O
P
CH2OH
CH2
CH2
O
P
O
P
O
CH2
O
C
O
CH2OH
O
P
C
H
C
O
CHOH
CH2
O
CHOH
CH2
O
P
O–
C
O
CHOH
P
O
CH2
8
Phosphoglyceromutase
P
O
O
ADP
Phosphoglycerate
kinase
3-Phosphoglycerate
(3PG)
8–9. Removal of water yields
two PEP molecules, each
with a high-energy
phosphate bond.
10. Removal of high-energy
phosphate by two ADP
molecules produces two
ATP molecules and two
5
2-Phosphoglycerate
6. Oxidation followed by
phosphorylation produces
two NADH molecules and
two molecules of BPG,
each with one
high-energy phosphate
bond.
4
Isomerase
O–
H
C
O
C
O
P
CH2OH
Phosphoenolpyruvate
4–5. The 6-carbon molecule
is split into two 3-carbon
molecules—one G3P,
another that is converted
into G3P in another
reaction.
Aldolase
CH2
Glyceraldehyde
3-phosphate
Hexokinase
ADP
1,3-Bisphospho- Dihydroxyacetone
Fructose
Fructose
glycerate
Phosphate
1,6-bisphosphate 6-phosphate
Glucose
6-phosphate
1
ATP
Krebs
Cycle
O
3-Phosphoglycerate
ATP
O–
C
O
C
O
P
CH2
O–
Pyruvate
Glycolysis
C
O
C
O
CH3
7
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Without oxygen
Pyruvate
H2O
O2
With oxygen
CO2
NAD+
NADH
NADH
Acetaldehyde
ETC in mitochondria
Acetyl-CoA
NAD+
NADH
Lactate
NAD+
Krebs
Cycle
Ethanol
8
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Glycolysis
Pyruvate Oxidation
NADH
Krebs
Cycle
Electron Transport Chain
Chemiosmosis
Pyruvate Oxidation: The Reaction
Pyruvate
Pyruvate
O–
C
O
C
O
CH 3
CO2
NADH
CoA
Acetyl Coenzyme A
Acetyl Coenzyme A
NAD+
S
CoA
C
O
CH3
9
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Glycolysis
Pyruvate Oxidation
CoA(Acetyl-CoA)
CoA
NADH
FADH2
Krebs
Cycle
4-carbon
molecule
(oxaloacetate)
ATP
Electron Transport Chain
Chemiosmosis
6-carbon molecule
(citrate)
NADH
NAD +
NADH
NAD+
SEGMENT A
Pyruvate from glycolysis is
oxidized into an acetyl group that
feeds into the citrate cycle. 2-C
acetyl group combines with 4-C
oxaloacetate to produce the 6-C
compound citrate.
SEGMENT B
Oxidation reactions produce
NADH. The loss of two CO2's
leaves a new 4-C compound. 1
ATP is directly generated for
each acetyl group fed in.
SEGMENT C
Two additional oxidations
generate another NADH and an
FADH2 and regenerate the
original 4-C oxaloacetate.
CO2
4-carbon
molecule
Krebs Cycle
5-carbon
molecule
NAD+
FADH2
NADH
FAD
CO2
4-carbon
molecule
4-carbon
molecule
ATP
ADP +
P
10
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Glycolysis
1. Reaction 1: Condensation
2–3. Reactions 2 and 3: Isomerization
Pyruvate Oxidation
4. Reaction 4: The first oxidation
5. Reaction 5: The second oxidation
NADH
Krebs
Cycle
FADH2
ATP
6. Reaction 6: Substrate-level phosphorylation
7. Reaction 7: The third oxidation
Electron T ransport Chain
Chemiosmosis
8–9. Reactions 8 and 9: Regeneration of
oxaloacetate and the fourth oxidation
Krebs Cycle: The Reactions
— — —
Malate (4C)
COO—
HO— CH
O═C
CH2
9
COO—
═
CH3— C— S
Citrate (6C)
COO—
CoA-SH
— — — —
NAD+
Oxaloacetate (4C)
COO—
— — —
NADH
—
Acetyl-CoA
O CoA
1
CH2
Citrate
synthetase
HO— C — COO—
Malate
dehydrogenase
CH2
CH2
COO—
COO—
2
H2O
Aconitase
3
8 Fumarase
Isocitrate (6C)
Fumarate (4C)
COO—
— — — —
— ═ —
COO—
CH
CH2
HC — COO—
HC
COO—
HO — CH
COO—
FADH2
FAD
7
Succinate
dehydrogenase
Isocitrate
dehydrogenase 4
Succinate (4C)
NAD+
CO2
COO—
— — —
NADH
CH2
-Ketoglutarate (5C)
CoA-SH
Succinyl-CoA
synthetase
GTP
ADP
6
GDP + Pi
CO2
COO—
CH2
CH2
C═ O
ATP
COO—
Succinyl-CoA (4C)
S — CoA
CH2
-Ketoglutarate
dehydrogenase
5
CoA-SH
— — — —
COO—
— — — —
CH2
CH2
C —O
NAD+
COO—
NADH
11
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Glycolysis
Pyruvate Oxidation
Krebs
Cycle
ATP
Electron Transport Chain
Chemiosmosis
H++
H
ATP
Mitochondrial matrix
NADH dehydrogenase
NADH + H+
Cytochrome
oxidase complex
bc1 complex
2H+ + 1/2O2
NAD+
ATP
synthase
ADP + Pi
H2O
FADH2
2 e– FAD
22 e–
22 e–
Q
Inner
mitochondrial
membrane
C
H+
H+
H+
H+
Intermembrane space
a. The electron transport chain
b. Chemiosmosis
12
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H+
Mitochondrial
matrix
ATP
ADP+Pi
Catalytic head
Stalk
Rotor
Intermembrane
space
H+
H+
H+
H+
H+
H+
13
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Glycolysis
NADH
Glucose
2 ATP
Pyruvate
Pyruvate
Oxidation
NADH
CO2
Acetyl-CoA
NADH
CO2
Krebs
Cycle
e-
H+
32 ATP
FADH2
2 ATP
eH2O
2H+
+
1/ O
2 2
e-
Q
C
H+
H+
H+
14
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Glucose
2 ATP
2
ATP
6
ATP
Glycolysis
Pyruvate
2
NADH
Chemiosmosis
Pyruvate oxidation
Krebs
Cycle
2
6
NADH
NADH
6
ATP
2
ATP
18
ATP
Chemiosmosis
2
FADH2
4
ATP
Total net ATP yield = 38
(36 in eukaryotes)
15
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Glycolysis
Glucose
ADP
Activates
Fructose 6-phosphate
Phosphofructokinase
Inhibits
Inhibits
Fructose 1,6-bisphosphate
Pyruvate
Pyruvate Oxidation
Pyruvate dehydrogenase
ATP
Acetyl-CoA
Inhibits
Citrate
Krebs
Cycle
NADH
Electron Transport Chain
and
Chemiosmosis
16
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Alcohol Fermentation in Yeast
H
H
C
OH
2 ADP
CH3
2 NAD+
2 ATP
2 Ethanol
2 NADH
O–
C
H
O
C
O
C
CO2
CH3
O
CH3
2 Acetaldehyde
Lactic Acid Fermentation in Muscle Cells
O–
2 ADP
H
2 ATP
2 NAD+
O–
C
O
C
OH
CH3
2 Lactate
2 NADH
C
O
C
O
CH3
17
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Macromolecule
degradation
Nucleic acids
Proteins
Polysaccharides
Lipids and fats
Cell building blocks
Nucleotides
Amino acids
Sugars
Fatty acids
Glycolysis
-oxidation
Deamination
Oxidative respiration
Pyruvate
Acetyl-CoA
Krebs
Cycle
Ultimate metabolic products
NH3
H2O
CO2
18
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Urea
NH3
19