Cell Metabolism and Product Formation

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Cell Metabolism and Product Formation
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Metabolic pathways

• catabolism

• anabolism

proteins, carbohydrates lipids, nucleic acids
glucose energy
amino acids, sugars fatty acids, nucleic acids
amino acids, sugars fatty acids, nucleic acids
glucose
proteins, carbohydrates lipids, nucleic acids
intermediates
CO2, H2O, energy
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Energy storage in cell

• adenosine triphosphate (ATP)

ATP H2O ADP Pi
?Go -7.3 kcal/mol
ADP H2O AMP Pi
?Go -7.3 kcal/mol
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Glycolysis via Embden-Meyerhof-Parnas (EMP)
pathway
glucose
EMP pathway
pyruvic acid ATP
Krebs, tricarboxylic acid, citric acid cycle
CO2 H2O NADH e-
O2
electron transport chain, respiration
water ATP
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Important coenzymes
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Oxidation Reduction reactions (redox)
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EMP Pathway
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Overall reaction in glycolysis
glucose 2 ADP 2 NAD 2 Pi 2
pyruvate 2 ATP 2 NADH H
net yield is 2 mol ATP/mol glucose
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acetyl-CoA 3NAD FAD ADP Pi 2H2O
CoA 3(NADHH) FADH2 ATP 2CO2
TCA cycle
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Respiration Electron transport chain, O2 as
terminal electron acceptor
ATP
ATP
ATP
Cyt b
Cyt c
Cyt a
Cyt a3
ADP
ADP
ADP
2H
protons and electrons
electrons (negative ? positive e- potential)
1.14V reduction potential
Theoretically 4 ATP/2H 2e- Eucaryotes
Typically 3 ATP Procaryotes Typically 1 ATP
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Summary
glucose 36 Pi 36 ADP 6 O2
6 CO2 6 H2O 36 ATP
36 ATP 263 kcal/mol glucose free energy change
is 686 kcal/mol energy efficiency of glycolysis
is 38 (under standard conditions) real
efficiency gt60