Cell respiration

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Cell respiration

• Definition
• The series of chemical reactions in cells which
  oxidize food energy (Carbohydrates, proteins,
  lipids) into cell energy (ATP) and heat may
  occur with or without O2 being used as the
  terminal electron acceptor (aerobically or
  anaerobically)
• General equation
• Glucose O2 ? CO2 H2O ATP Heat

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The bottom line of cell respiration is the
production of ATP (cell energy)

• ATP can be produced in 1 of 3 ways
• Substrate-level phosphorylation
• Essentially, Food-P ADP ? food ATP
• 2) Oxidative phosphorylation
• Occurs as NADH2 and FADH2 relay e-s to an
  ETC, setting up an electrochemical gradient of
  Hs which is relieved by ATPase which uses
  kinetic energy of proton flow to form ATP from
  ADP Pi
• 3) Photophosphorylation during photosynthesis

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Substrate-level phosphorylation -occurs during
the rxns of Glycolysis and the Krebs Cycle
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Oxidative Phosphorylation occurs during the rxns
of the Electron Transport Chain along inner
membrane (cristae) of the mitochondrion
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The complete oxidation of foodAerobic respiration

• Equation Glucose O2 ? CO2 H2O energy
• The above set of reactions occur in 4 distinct
  steps
• Glycolysis splits 6-C glucose into 2 X 3-C
  pyruvic acids (pyruvates)
• Pyruvate oxidation removes 1 C from each
  pyruvate to form 2 X 2-C acetyl groups which may
  enter the rxns of the Krebs Cycle
• Krebs Cycle cyclical series of rxns which break
  down each of the 2-C acetyl groups into 2 CO2
• Electron Transport Chain electron carrying
  coenzymes relay their e-s to a series of
  electron carrying proteins to O2 setting up an
  electrochemical gradient which is relieved
  through ATPase which transforms the kinetic
  energy of proton flow into ATP formation

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During each step of the process, energy is
released!!

• In Glycolysis 4 total ATPs are formed (yet,
  there is only a net gain of 2 ATPs) and 2 NAD
  coenzymes are reduced to NADH2
• In Pyruvate oxidation 2 NADH2s are produced
• In the Krebs Cycle 2 ATPs are formed, 6 NADH2s
  are produced, and 2 FADH2s
• In Electron Transport 32 ATPs are formed as 10
  NADH2s and 2 FADH2s are oxidized back to NAD
  and FAD and recycled back to the system and
  re-used

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4
1
ETC
2
3
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The reactions of cell respirationGlycolysis
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The reactions of cell respirationPyruvate
oxidation
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The reactions of cell respirationthe Krebs Cycle
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the Electron Transport Chain
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Overview of aerobic respiration

• General equation glucose O2 ? CO2 H2O
  energy
• Glucose is oxidized (broken down) to form 6 CO2
• E-s stripped away from glucose are relayed to
  ETC by NAD and FAD coenzymes and accepted by O2
• O2 is the terminal electron acceptor
• ETC relays e-s and pumps Hs (protons)
• H outside of ETC membrane is relieved by
  ATPase
• Hs flow through ATPase
• ATPase transforms kinetic flow of Hs into bond
  between ADP and P