Download Electrons from food High energy Low energy 2H+ Energy released

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Electrons from food
2e–
Oxidation
Energy-rich
molecule
Enzyme
H
Energy released
for ATP synthesis
Product
Reduction
High energy
H
+H+
H
H
H
H
2e–
H+
H
NAD+
NAD+
H
NAD
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.
Low energy
3. NADH diffuses away
and can then donate
electrons to other
molecules.
1/ O
2 2
2H+
H 2O
1
2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Reduction
2H
Oxidation
H+
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
PEP
Pyr
uva
te
P
Enzyme
P
P
Enzyme
P
P
– ADP
– ATP
P
Ad
Adenosine
3
eno
sin
e
4
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glycolysis
Glucose
NADH
ATP
ATP
NADH
Outer
mitochondrial
membrane
Glycolysis
Pyruvate Oxidation
Intermembrane
space
Krebs
Cycle
Electron Transport Chain
Chemiosmosis
Pyruvate
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.
Pyruvate
Oxidation
NADH
Priming Reactions
6-carbon glucose
(Starting material)
Mitochondrial
matrix
Acetyl-CoA
ATP
ATP
ADP
CO2
P
ADP
P
Cleavage
6-carbon sugar diphosphate
CO2
NADH
Krebs
Cycle
e–
NAD+ FAD O2
P
ATP
H 2O
e– Electron e–
Transport Chain
ATP
Inner
mitochondrial
membrane
3-carbon sugar
phosphate
P
3-carbon sugar
phosphate
Pi
Pi
NAD+
Oxidation and ATP Formation
FADH2
Chemiosmosis
ATP Synthase
H+
NAD+
NADH
NADH
ADP
ADP
ATP
ATP
ADP
ADP
ATP
ATP
3-carbon
pyruvate
5
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
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
CH2OH
Glycolysis: The Reactions
Glucose
Pyruvate Oxidation
ADP
Glucose 6-phosphate
Fructose 6-phosphate
1,3-Bisphospho- Dihydroxyacetone
Fructose
glycerate
Phosphate
1,6-bisphosphate
3
ATP
Phosphofructokinase
ADP
Fructose 1,6-bisphosphate
2–3. Rearrangement,
followed by a second
ATP phosphorylation.
4
Aldolase
5
Isomerase
4–5. The 6-carbon molecule
is split into two 3-carbon
molecules—one G3P,
another that is converted
into G3P in another
reaction.
Dihydroxyacetone
phosphate
Pi
NAD+
Pi
NADH
6. Oxidation followed by
phosphorylation produces
two NADH molecules and
two molecules of BPG,
each with one
high-energy phosphate
bond.
NADH
Glyceraldehyde
3-phosphate
dehydrogenase
1,3-Bisphosphoglycerate
1,3-Bisphosphoglycerate
(BPG)
(BPG)
7. Removal of high-energy
phosphate by two ADP
molecules produces two
ATP molecules and leaves
two 3PG molecules.
Phosphoglycerate
kinase
7
ATP
3-Phosphoglycerate
(3PG)
CH2
ATP
CH2
O
C
O
CH2OH
O
P
2-Phosphoglycerate
(2PG)
C
Phosphoenolpyruvate Phosphoenolpyruvate
(PEP)
(PEP)
C
H
C
O2
O
NADH
NADH
Acetaldehyde
CHOH
CH2
ETC in mitochondria
NADH
NAD+
Acetyl-CoA
O
P
O
CHOH
NAD+
Lactate
P
O
CH2
O–
H
C
O
C
O
Krebs
Cycle
P
O–
C
O
C
O
Ethanol
P
CH2
O–
ADP
10
Pyruvate kinase
Pyruvate
P
CO2
NAD+
O–
Pyruvate
ADP
ATP
O
With oxygen
H 2O
O
CH2
Phosphoenolpyruvate
H 2O
Enolase
P
CH2OH
9
H 2O
O
CHOH
2-Phosphoglycerate
Phosphoglyceromutase
2-Phosphoglycerate
(2PG)
10. Removal of high-energy
phosphate by two ADP
molecules produces two
ATP molecules and two
CH2
O
ADP
3-Phosphoglycerate
(3PG)
CH2OH
CH2
8
8–9. Removal of water yields
two PEP molecules, each
with a high-energy
phosphate bond.
Without oxygen
Pyruvate
P
O
O
O
P
3-Phosphoglycerate
ADP
P
O
O
P
Glyceraldehyde 3phosphate (G3P)
6
NAD+
CH2
Fructose
6-phosphate
Phosphoglucose
isomerase
2
Electron Transport Chain
Chemiosmosis
1. Phosphorylation of
glucose by ATP.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glucose
6-phosphate
Hexokinase
Krebs
Cycle
O
1
ATP
Glyceraldehyde
3-phosphate
ATP
Glucose
Glycolysis
NADH
ATP
Pyruvate
C
O
C
O
CH3
7
8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glycolysis
Glycolysis
Pyruvate Oxidation
Pyruvate Oxidation
NADH
NADH
Krebs
Cycle
Krebs
Cycle
FADH2
CoA(Acetyl-CoA)
6-carbon molecule
(citrate)
NADH
Electron Transport Chain
Chemiosmosis
Electron Transport Chain
Chemiosmosis
CoA
4-carbon
molecule
(oxaloacetate)
ATP
SEGMEN
NAD +
TA
NADH
NAD+
Pyruvate
O–
Pyruvate
C ⎯
⎯ O
C ⎯
⎯ O
Acetyl Coenzyme A
NAD+
NADH
CoA
Acetyl Coenzyme A
S
4-carbon
molecule
CoA
CH3
5-carbon
molecule
NAD+
T
EN
B
NADH
GM
SE
FAD
4-carbon
molecule
4-carbon
molecule
SEGMENT C
Two additional oxidations
generate another NADH and an
FADH2 and regenerate the
original 4-C oxaloacetate.
C ⎯
⎯ O
Krebs Cycle
FADH2
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.
CH 3
CO2
CO2
SEGMENT C
Pyruvate Oxidation: The Reaction
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.
ATP
ADP +
CO2
P
9
10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glycolysis
1. Reaction 1: Condensation
2–3. Reactions 2 and 3: Isomerization
Pyruvate Oxidation
Glycolysis
4. Reaction 4: The first oxidation
NADH
5. Reaction 5: The second oxidation
Krebs
Cycle
FADH2
ATP
6. Reaction 6: Substrate-level phosphorylation
Pyruvate Oxidation
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
Krebs
Cycle
O═ C
CH2
9
Malate
dehydrogenase
CH2
COO—
═
CH3— C— S
1
Citrate (6C)
CH2
Citrate
synthetase
HO— C — COO—
CH2
H++
COO—
COO—
Mitochondrial matrix
2
H 2O
Aconitase
8 Fumarase
3
NADH dehydrogenase
NADH + H+
— — — —
— ═ —
COO—
CH
2H+ + 1/2O2
NAD+
CH2
HC
2
HO — CH
FADH2
COO—
7
Succinate
dehydrogenase
Isocitrate
dehydrogenase 4
Succinate (4C)
ADP
6
GDP + Pi
CO2
COO—
CH2
CH2
C═ O
ATP
COO—
Succinyl-CoA (4C)
— — — —
GTP
S — CoA
CH2
CoA-SH
NAD+
FAD
22 e–
C
H+
H+
H+
H+
Intermembrane space
CH2
α-Ketoglutarate
dehydrogenase
5
— — — —
— — —
Succinyl-CoA
synthetase
COO—
Inner
mitochondrial
membrane
α-Ketoglutarate (5C)
CoA-SH
CH2
ADP + Pi
H 2O
Q
NADH
CH2
e–
22 e–
NAD+
CO2
COO—
ATP
ATP
synthase
FADH2
HC — COO—
COO—
Cytochrome
oxidase complex
bc1 complex
Isocitrate (6C)
Fumarate (4C)
COO—
FAD
ATP
Electron Transport Chain
Chemiosmosis
COO—
CoA-SH
— — — —
— — —
— — —
Malate (4C)
COO—
HO— CH
NAD+
Oxaloacetate (4C)
COO—
—
Acetyl-CoA
O CoA
NADH
C —O
a. The electron transport chain
COO—
b. Chemiosmosis
NADH
11
12
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glycolysis
H+
Mitochondrial
matrix
NADH
Glucose
2 ATP
Pyruvate
ATP
Pyruvate
Oxidation
NADH
ADP+Pi
CO2
Acetyl-CoA
Catalytic head
NADH
e-
CO2
Krebs
Cycle
FADH2
32 ATP
e-
Stalk
H+
2 ATP
H 2O
2H+
+
1
/2O2
e-
Q
C
Rotor
H+
H+
H+
Intermembrane
space
H+
H+
H+
H+
H+
H+
13
14
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glycolysis
Glucose
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glucose
2 ATP
2
ATP
6
ATP
ADP
Activates
Fructose 6-phosphate
Glycolysis
Phosphofructokinase
Pyruvate
2
NADH
Inhibits
Inhibits
Fructose 1,6-bisphosphate
Chemiosmosis
Pyruvate oxidation
2
NADH
6
ATP
2
ATP
18
ATP
Pyruvate
Pyruvate Oxidation
Pyruvate dehydrogenase
ATP
Krebs
Cycle
6
NADH
Acetyl-CoA
Inhibits
Chemiosmosis
2
FADH2
4
Krebs
Cycle
ATP
Citrate
NADH
Total net ATP yield = 38
(36 in eukaryotes)
Electron Transport Chain
and
Chemiosmosis
15
16
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Alcohol Fermentation in Yeast
Macromolecule
degradation
H
H
2 ADP
C
OH
Nucleic acids
Proteins
Polysaccharides
Lipids and fats
CH3
2 NAD+
2 ATP
2 Ethanol
Cell building blocks
Nucleotides
Amino acids
Sugars
Fatty acids
2 NADH
O–
H
C
O
C
O
C
CO2
CH3
Deamination
O
Glycolysis
β-oxidation
Oxidative respiration
CH3
2 Acetaldehyde
Pyruvate
Lactic Acid Fermentation in Muscle Cells
Acetyl-CoA
O–
2 ADP
H
2 ATP
2
O–
NAD+
C
O
C
OH
Krebs
Cycle
CH3
2 Lactate
2 NADH
C
O
C
O
Ultimate metabolic products
NH3
H 2O
CO2
CH3
17
18
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Urea
NH3
19