Chapter 14 Glycolysis Part 2

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Chapter 14 Glycolysis Part 2
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• Important points
• Glycolysis is a very important
• pathway in the metabolism of glucose.
• In glycolysis, 1 molecule of glucose is
• converted into 2 molecules of pyruvate
• with the net formation of 2 molecules
• of NADH and 2 molecules of ATP

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• Pyruvate can participate in several
• different pathways
• a. Aerobic respiration which produced
• many molecules of ATP
• b. Anaerobic alcohol fermentation
• with the production of 2 ethanol,
• 3 carbon dioxide and 2 ATP
• b. Anaerobic glycolysis (or lactate
• fermentation with the production
• of 2 molecules of lactate and 2
• ATP.

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• Glycolysis can be divided into
• two phases (1) energy-requiring and
• (2) energy-releasing.

• The energy-requiring steps require
• 2 ATP and result in the production of
• 1 fructose-1,6-bisphosphate.

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Glyceraldehyde 3-phosphate dehydrogenase
H
High energy bond
Glyceradehyde 3-P
Aldehyde
Reduction
1,3-bisphosphoglycerate
Oxidation
Acid
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Phosphoglycerate kinase
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ATP is formed by substrate phosphorylation
Directly by an enzymatic reaction
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What is the DGo ?
1,3-bisphosphoglycerate?3-phosphoglycerate Pi
DGo -11.8 kcal/mol
ADP Pi ? ATP
DGo 7.3 kcal/mole
1,3-bisphosphoglycerate ADP ?
3-phosphoglycerate ATP
DGo -4.5 kcal/mol
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Phosphoglyceromutase
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Types of reactions

• Mutase moves a group from one C to
• another.

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Enolase
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Pyruvate kinase
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pyruvate
Substrate level phosphorylation
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Energetics
Phosphoenolpyruvate ? Pyruvate Pi
DGo -14.8 kcal/mole
ADP Pi ? ATP
DGo 7.3 kcal/mole
Phosphoenolpyruvate ADP ? Pyruvate ATP
DGo - 7.5 kcal/mole
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ATP Summary
-1 ATP
2 ATP net
- 1 ATP
2 NADH
2 ATP
Fig. 14.10
2 ATP
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• Regulation
• Why?
• Where?
• At a point where the substrate is
  committed
• to a pathway
• At an irreversible step

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Hexokinase Glucose-6-P
PhosphofructokinaseATP
Pyruvate kinase ATP
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• Regulation
• Why?

2. Where? At a point where a substrate is
committed to a pathway At an
irreversible step

• What inhibits?
• Products
• ATP, glucose 6-P

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Glucose Metabolism
Glucose (6C) 2 Pyruvate (3C)
2ATP
2NADH
Glycolysis
4ATP
2ATP
2 ATP
6CO2
8NADH 2FADH2
Ethanol CO2
Lactate (3C)
Anaerobic glycolysis
2ATP
Anaerobic alcohol Fermentation
Aerobic Respiration
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Lactic Acid Fermentation- Anaerobic Glycolysis
Lactate dehydrogenase
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Energy Balance
Conversion of glucose to pyruvate produces
2ATP
2 NADH
Conversion of pyruvate to lactate requires 2
NADH
Net in lactate production 2ATP only
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Alcohol fermentation
Pyruvate ? acetaldehyde CO2
Pyruvate decarboxylase
Acetaldehyde NADH H? ethanol NAD
Alcohol dehydrogenase
Net (glucose?ethanol) 2 ATP
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Energetics
Glucose? Lactate 2ATP -14.6 kcal/mol

Glucose? Pyruvate 2ATP 2NADH -29.5
Glucose? Oxygen 38 ATP -277 kcal