oxidation reduction product...as a cofactor for oxidation reactions bind nad+ and the substrate. 2....
TRANSCRIPT
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Product
Enzyme
NAD+
NAD+ NAD NAD
2e–
H+
+H+
Energy-rich molecule
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.
Reduction
Oxidation
H H
H H H
H
H H
1
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2e– Electrons from food
High energy
Low energy
2H+ 1 / 2 O2
Energy released for ATP synthesis
H2O
2
2H H+
Reduction
Oxidation
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3
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– ADP
Enzyme Enzyme
– ATP
PEP Pyruvate
P
P P
P
P
Adenosine
P
4
Outer mitochondrial
membrane
Intermembrane space
Mitochondrial matrix
CO2
ATP H2O FAD O2
Inner mitochondrial
membrane
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ATP
e– Electron
Transport Chain Chemiosmosis ATP Synthase
e–
H+
e– NAD+
NADH
Glycolysis
Pyruvate
Glucose
Pyruvate Oxidation
Acetyl-CoA NADH
Krebs Cycle
CO2
ATP
NADH
FADH2
5
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Glycolysis
NADH
Pyruvate Oxidation
ATP
Electron Transport Chain Chemiosmosis
Krebs Cycle
6-carbon sugar diphosphate
NAD+ NAD+
Pri
min
g R
eact
ion
s C
leav
age
Oxi
dat
ion
an
d A
TP
Fo
rmat
ion
STEPS C and D
NADH NADH
P P
P P
STEP A
ATP ATP
ADP ADP
STEP B
3-carbon sugar phosphate
3-carbon sugar phosphate
Pi Pi
ADP ADP
ATP ATP
ATP
ADP ADP
ATP
3-carbon pyruvate
3-carbon pyruvate
6-carbon glucose (Starting material)
Glycolysis begins with the addition of energy. Two high- energy phosphates (P) from two molecules of ATP are added to the 6-carbon molecule glucose, producing a 6-carbon molecule with two phosphates.
Then, the 6-carbon molecule with two phosphates is split in two, forming two 3-carbon sugar phosphates.
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.
6
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NADH NAD+ NADH Pi NAD+
Glucose Hexokinase
Phosphofructokinase
Glucose 6-phosphate
Fructose 6-phosphate
Fructose 1,6-bisphosphate Isomerase Aldolase
Pyruvate Pyruvate
Enolase
Pyruvate kinase
AD P
10
Glu
cose
Gly
cera
ldeh
yde
3-p
ho
sph
ate
Pyr
uva
te
Glycolysis: The Reactions Glycolysis NADH
Pyruvate Oxidation
H2O
ATP
ADP
Electron Transport Chain Chemiosmosis
Krebs Cycle
ATP
ATP
Phosphoglucose isomerase
Glyceraldehyde 3- phosphate (G3P)
Dihydroxyacetone phosphate
1. Phosphorylation of glucose by ATP.
2–3. Rearrangement, followed by a second ATP phosphorylation.
4–5. The 6-carbon molecule is split into two 3-carbon molecules—one G3P, another that is converted into G3P in another reaction.
6. Oxidation followed by phosphorylation produces two NADH molecules and two molecules of BPG, each with one high-energy phosphate bond.
7. Removal of high-energy phosphate by two ADP molecules produces two ATP molecules and leaves two 3PG molecules.
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
1,3-Bisphosphoglycerate (BPG)
1,3-Bisphosphoglycerate (BPG)
Glyceraldehyde 3-phosphate
dehydrogenase
Pi
ADP
Phosphoglycerate kinase
ADP
ATP
3-Phosphoglycerate (3PG)
3-Phosphoglycerate (3PG)
2-Phosphoglycerate (2PG)
2-Phosphoglycerate (2PG)
H2O
ATP
Phosphoenolpyruvate (PEP)
Phosphoenolpyruvate (PEP)
ADP ADP
ATP ATP
Ph
osp
ho
eno
l-
pyr
uva
te
3-P
ho
sph
o-
gly
cera
te
1,3-
Bis
ph
osp
ho
- g
lyce
rate
G
luco
se
6-p
ho
sph
ate
Fru
cto
se
6-p
ho
sph
ate
Fru
cto
se
1,6-
bis
ph
osp
hat
e D
ihyd
roxy
acet
on
e P
ho
sph
ate
2-P
ho
sph
o-
gly
cera
te
CH2OH O
CH2 O O P
CH2 O O P
CH2OH
O CH2 CH2 O O P P
CHOH H C O CH2 O P
C O O CH2 P CH2OH
CHOH O C O CH2 O
P P
CHOH O–
C O CH2 O P
H C O O–
C O CH2OH P
C O O–
C O CH2
P
C O O–
C O CH3
8
9
10
7
4 5
3
2
1
6
Phosphoglyceromutase
7
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Without oxygen
NAD+
O2 NADH
ETC in mitochondria
Acetyl-CoA
Ethanol
NAD+
CO2
NAD+
H2O
Lactate
Pyruvate
Acetaldehyde NADH
NADH
With oxygen
Krebs Cycle
8
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Glycolysis
Pyruvate Oxidation
NADH
Krebs Cycle
Electron Transport Chain Chemiosmosis
Pyruvate Oxidation: The Reaction
NAD+
CO2
CoA
Acetyl Coenzyme A
Pyruvate
Pyr
uva
te
Ace
tyl C
oen
zym
e A
O
CH 3
C
O–
C O ⎯⎯
⎯⎯
S CoA
CH3
O C ⎯⎯
NADH
9
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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.
CoA- (Acetyl-CoA)
CoA
4-carbon molecule
(oxaloacetate) 6-carbon molecule
(citrate)
NAD +
NADH
CO2
5-carbon molecule
NAD+
NADH
CO2
4-carbon molecule
ADP + P
Krebs Cycle
FAD
FADH2
4-carbon molecule
NAD+
NADH
SEGMENT C Two additional oxidations generate another NADH and an FADH2 and regenerate the original 4-C oxaloacetate. ATP
Glycolysis
Pyruvate Oxidation
Electron Transport Chain Chemiosmosis
NADH
FADH2
Krebs Cycle
ATP
SEGMENT A
SE
GM
EN
T C
4-carbon molecule
10
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Glycolysis
NADH
F ADH2
Pyruvate Oxidation
ATP
Krebs Cycle: The Reactions
Citrate synthetase
NAD+
NADH
H2O
NAD+
NADH
CO2
F AD Isocitrate dehydrogenase
Fumarase
CoA-SH 1
2
Aconitase 3
4
8
9
7
CoA-SH
NAD+
CO2
5
6
NADH
CoA-SH
GDP + Pi
Acetyl-CoA
═
CH3 — C — S
O CoA —
Krebs Cycle
Malate dehydrogenase
α-Ketoglutarate dehydrogenase
Succinyl-CoA synthetase
GTP
ATP
ADP
Succinate dehydrogenase
FADH2
8–9. Reactions 8 and 9: Regeneration of oxaloacetate and the fourth oxidation
7. Reaction 7: The third oxidation
6. Reaction 6: Substrate-level phosphorylation
5. Reaction 5: The second oxidation
4. Reaction 4: The first oxidation
2–3. Reactions 2 and 3: Isomerization
1. Reaction 1: Condensation
Electron T ransport Chain Chemiosmosis
Oxaloacetate (4C)
CH2
O ═ C
COO—
COO—
—
—
—
Citrate (6C)
HO — C — COO—
COO—
COO—
CH2
CH2
—
—
—
—
Isocitrate (6C)
HC — COO—
COO—
COO—
CH2
HO — CH
—
—
—
—
α-Ketoglutarate (5C)
CH2
COO—
COO—
CH2
C — O —
—
—
—
Succinyl-CoA (4C)
CH2
COO—
S — CoA
CH2
C ═ O
—
—
—
—
Succinate (4C)
COO—
CH2
COO—
CH2
—
—
—
Fumarate (4C)
HC
CH
═
COO—
COO—
—
—
Malate (4C)
HO — CH
COO—
CH2
COO—
—
—
—
11
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Mitochondrial matrix
NADH + H+
ADP + Pi
H2O
H+ H+
2H+ + 1 / 2 O2
Glycolysi s
Pyruvate Oxidatio n
2
Krebs Cycle ATP
Electron Transport Chain Chemiosmosis
NADH dehydrogenase bc1 complex Cytochrome
oxidase complex
FAD
Inner mitochondrial membrane
Intermembrane space
a. The electron transport chain
ATP synthase
ATP
b. Chemiosmosis
NAD+
Q
C
e–
FADH2
H+ H+
H+ H+
e– 2 2 e– 2 2
12
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ADP+Pi
Catalytic head
Stalk
Rotor
H+
H+
Mitochondrial matrix
Intermembrane space
H+ H+
H+
H+ H+
ATP
13
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H2O
CO2
CO2
H+
H+
2H+
+ 1 / 2 O2
H+
e-
H+
32 ATP Krebs Cycle
2 ATP
NADH
NADH
FADH2
NADH
Pyruvate Oxidation
Acetyl-CoA
e-
Q
C
e-
Glycolysis
Glucose
Pyruvate
2 ATP
14
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Chemiosmosis
Chemiosmosis
2 6
2 4
6 18
2
2
2 6 NADH
NADH
NADH
Total net ATP yield = 38 (36 in eukaryotes)
ATP
ATP
ATP
ATP
ATP
ATP
Krebs Cycle
Pyruvate oxidation
FADH2
Glycolysis 2
Glucose
Pyruvate
ATP
15
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Glucose
Acetyl-CoA
Fructose 6-phosphate
Fructose 1,6-bisphosphate
Pyruvate
Pyruvate Oxidation
Krebs Cycle
Electron Transport Chain and
Chemiosmosis
Citrate
ADP
ATP
NADH
Inhibits
Inhibits
Activates
Inhibits
Phosphofructokinase
Pyruvate dehydrogenase
Glycolysis
16
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CO2
2 Acetaldehyde
2 AD P
2 Lactate
Alcohol Fermentation in Yeast
2 ADP
Lactic Acid Fermentation in Muscle Cells
2 NAD+
2 NAD+
2 NADH
2 NADH
2 ATP
2 ATP
C O
C O
O–
CH3
C O
H
CH3
C O
C O
CH3
O–
CH3
H C OH
C O
O–
H
2 Ethanol
H C OH
CH3
17
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Cell building blocks
Deamination β-oxidation
Glycolysis
Oxidative respiration
Ultimate metabolic products
Acetyl-CoA
Pyruvate
Macromolecule degradation
Krebs Cycle
Nucleic acids Polysaccharides
Nucleotides Amino acids Fatty acids Sugars
Proteins Lipids and fats
NH3 H2O CO2
18
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Urea
NH3
19