Bioenergetics: Energy Release from Food

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Bioenergetics Energy Release from Food

• McArdle, Katch, Katch, 3rd ed.
• Chapter 5
• Part 3

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Energy Release from CHO

• Primary function CHO is ___?
• CHO is only nutrient can be used ____?
• During light moderate intensity aerobic
  exercise, CHO supplies about ___ requirements.
• A continual breakdown of CHO required so lipid
  can be _____?
• Complete breakdown of one mole glucose
• C6H12O6 6 O2 ? __ CO2 __ H20 686 kcal
• 686 ? 7.3 kcal/mole 94 moles x .38 36 ATP

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Aerobic versus Anaerobic Energy from CHO

• Stage 1 Glycolysis anaerobic. Glucose to 2
  molecules pyruvic acid. No Oxygen.
• Stage 2 Citric Acid Cycle Electron Transport
  Chain aerobic. Pyruvic Acid to carbon dioxide
  and water.

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Stage 1 Anaerobic Energy from Glucose

• Glycolysis, Embden-Myerhof
• Glycolysis a series of 10 enzymatically
  controlled chemical rxns involving breakdown of
  ____ to 2 molecules ____.
• Glycogenolysis same series of rxns when start
  with ____, still ends with ___.
• Where does glycolysis occur?

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Energy Release from CHO

• Glycogen is storage form of glucose.
• Where is glycogen stored?

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Glycogen

• When ATPADP high, glucose phosphorylated
  polymerized to form glycogen.
• When ADPATP high, glycogen lysed to make
  glucose-1-phosphate then glucose 6-phosphate.

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Stage 1 Anaerobic Glycolysis

• How many ATP are resynthesized during
  substrate-level phosphorylation?
• Rate limiting step is fructose 6-phosphate to
  fructose 1, 6-diphosphate, which step?
• What is the rate-limiting enzyme?

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Stage 1 Anaerobic Glycolysis

• How many hydrogen atoms are stripped?
• Under aerobic conditions, NADH H shuttles
  hydrogens to FAD via glycerol phosphate shuttle
  to Electron Transport Chain.
• Under anaerobic conditions, NADH H shuttles
  Hs to ______?

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Stage 1 Glycolysis

• The formation of lactic acid occurs when excess
  Hs from NADH temporarily combine with pyruvate.
• Once lactate forms in muscle, quickly diffuses
  into blood for buffering.

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Stage 1 Glycolysis

• Glycolysis can continue to supply anaerobic
  energy for ATP re-synthesis temporarily.
• Increased intracellular acidity other
  disruptions mediate fatigue by inactivating
  various enzymes in energy transfer.

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Lactate Disposal

• Lactate NOT a waste product valuable fuel.
• Cori cycle removes lactate replenishes glycogen
  reserves.
• When sufficient oxygen available in muscle, NAD
  carries H from lactate for oxidation in ETC.

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Stage 2 Aerobic Energy from Glucose

• Citric acid cycle, Krebs cycle or tricarboxylic
  acid cycle occurs within mitochondria.
• How many chemical reactions are there?
• What is the most important function of citric
  acid cycle?
• How many ATP are made directly in citric acid
  cycle?

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Net Energy from Glucose

• Four extramitochondrial hydrogens (2 NADH) yield
  4 ATP.
• Four hydrogens (2 NADH) from pyruvate to
  acetyl-CoA yield 6 ATP.
• Twelve hydrogens from (6 NADH) citric acid cycle
  yields 18 ATP.
• Four hydrogens from FADH in citric acid cycle.

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Net Energy from Glucose

• 32 ATP from electron transport chain oxidation.
• 2 ATP from substrate level in glycolysis.
• 2 ATP from substrate level in citric acid cycle.

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Energy Release from Fat

• Fuel reserves from fat represents 60,000 to
  100,000 kcals in fat cells intramuscular fat
  triglycerides.
• CHO reserves is lt2,000 kcals.
• Lipolysis splits triacylglycerol molecule into
  _____ 3 ____ ____.

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Energy Release from Fat

• What happens to glycerol?
• How many ATP can a glycerol generate?
• Fatty acid undergoes transformation to acetyl CoA
  in mitochondria via ____?
• 147 moles ATP for each 18-C fatty acid.

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Energy from Fat

• Beta oxidation is aerobic process.
• Hydrogen atoms in fatty acids removed and
  transferred to coenzymes NAD FAD which carry to
  electron transport chain.

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Energy from Protein

• Protein can be used as energy substrate during
  ______ type exercise.
• To provide energy, amino acid must be converted
  to usable form.
• Two processes for nitrogen removal
• Removal of nitrogen _______
• Transfer of nitrogen to other compound ____
• Once amine group removed, remaining carbon
  skeleton becomes one of metabolic intermediates.

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Energy from Protein

• Some amino acids are glucogenic, when deaminated
  yield products for glucose synthesis.
• Some amino acids are ketogenic, when deaminated
  cannot synthesize to glucose but instead
  synthesize to triglyceride.

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Metabolic Mill

• Citric acid cycle essential connector between
  food ATP
• Notice reversibility of reactions except for
  acetyl CoA to pyruvate. Fatty acids do not make
  glucose

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Illustration References

• Axen, Kenneth and Kathleen Axen. 2001.
  Illustrated Principles of Exercise Physiology.
  Prentice Hall.
• McArdle, William D., Frank I. Katch, and Victor
  L. Katch. 2000. Essentials of Exercise
  Physiology 2nd ed. Image Collection. Lippincott
  Williams Wilkins.