Transcript Metabolism

Metabolism
Transformations and
Interactions
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Metabolism
• Photosynthesis
• Fuel
• Metabolism
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Chemical Reactions
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Adenosine Triphosphate
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Chemical Reactions
• Coupled reactions
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A Typical Cell
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Chemical Reactions
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Copyright 2005 Wadsworth Group, a division of Thomson Learning
Chemical Reactions
• Helpers in reactions
–Enzymes
•Cofactors
–Coenzymes
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Nutrients for Energy
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Nutrients for Energy
• Glycolysis
• Pyruvate  acetyl CoA
• TCA cycle
• Electron transport chain
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Glycolysis:
Glucose-toPyruvate
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Glucose
• The fate of pyruvate
–Anaerobic vs. aerobic pathways
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Glucose
• The fate of pyruvate
–Anaerobic
•Pyruvate-to-lactic acid
–Cori cycle
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Pyruvate-to-Lactic Acid (Anaerobic)
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Glucose
• The fate of pyruvate
–Aerobic
•Pyruvate-to-acetyl CoA
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Copyright 2005 Wadsworth Group, a division of Thomson Learning
Pyruvateto-Acetyl
CoA
(Aerobic)
The Paths of Pyruvate and Acetyl CoA
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Glucose yields energy
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Glycerol & Fatty Acids
• Glycerol-to-pyruvate
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Glycerol & Fatty Acids
• Fatty acids-to-acetyl CoA
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Fatty acids-to-acetyl CoA, cont’d
This repeating step is also known as beta-oxidation!
Fats Enter the Energy Pathway
Glycerol & Fatty Acids
• Fatty acids cannot be used to
synthesize glucose: Why is this
important??
Amino Acids
• Amino acids-to-acetyl CoA
Amino Acids
• Amino acids-to-glucose
Amino Acids
• Deamination
– Keto acid
– Ammonia
Amino Acids
• Transamination
Amino Acids
•
•
Ammoniato-urea
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Urea excretion via
the kidneys
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Copyright 2005 Wadsworth Group, a division of Thomson Learning
The Final Steps
• The TCA cycle
– Acetyl-CoA goes in and oxaloacetate
comes out...which ironically is used to
continue the cycle...?
– Many B vitmins used as cofactors.
– By-products go into the E- transport
chain.
–ATP generated along the way!
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson Learning
The TCA Cycle
The Final Steps
• The electron transport chain
- Consumes oxygen
- Produces carbon dioxide and water
- Produces energy as ATP!
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Electron Transport Chain and ATP Synthesis
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The Final Steps
• The kcalories-per-gram secret
revealed
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The Central
Pathways
of Energy
Metabolism
Energy Balance
• Feasting—Excess Energy
– Excess protein is converted to fat but this is inefficient
and indirect. Its priority is other roles.
– Excess carbohydrate is converted to fat but this is
inefficient and indirect. Its priority is glycogen stores.
– Excess fat is efficiently converted to fat.
• The transition from feasting
to fasting draws on
reserves.
Economics of
Feasting
Economics of Fasting
Economics of Fasting
• Glucose needed for the brain
• Protein meets glucose needs
• Suppression of appetite
• Slowing of metabolism
• Are you starving now??
Energy Balance
• Fasting—Inadequate Energy
– Symptoms of Starvation
• Muscle wasting
• Decreased heart rate, respiratory rate,
metabolic rate, and body temperature
• Impaired vision
• Organ failure
• Decreased immunity
• Depression, anxiety, and food-related
dreams...yes, if I was starving I would naturally dream about
food!