Cellular Respiration

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Cellular Respiration

• Grenades to Matchsticks

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Cellular RespirationOverview
Glucose Oxygen Carbon Water Dioxide

• This is the overall equation for cellular
  respiration- including glycolysis, Krebs ETC

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Energy Carriers

• The primary energy carrier is ATPlt--gtADP
• Excited electrons and protons are carried for
  further processing by electron carriers (just
  like photosynthesis!!!)
• NAD lt---gt NADH (cellular respiration)
• NADP lt-----gt NADPH (photosynthesis)

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ATP
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Aerobic Respiration Overview
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Glycolysis

• 1st Chemical Pathway
• Takes place in the cytoplasm
• 6-C glucose is cut into 2, 3-C molecules (pyruvic
  acid/pyruvate)
• Produces 4 ATP, uses 2 ATP for a net yield of 2
  ATP
• Produces 2 NADH

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Glycolysis 1

• The first set of reactions change glucose to G3P
  (phospho-glycer-aldehyde) also found in
  photosynthesis
• 2 molecules of ATP are used in this process

G3P
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Glycolysis 2

• The G3P molecules undergo more rxns
• They become 2 pyruvic acid molecules
• EACH G3P produces 2 ATP
• EACH G3P gives electrons to 1 NAD to make 2 NADH
• The net 2 ATP (4 made subtract 2 used) is only
  2 of glucoses total energy

G3P
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Totals from Glycolysis
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Transition Reactions

• Aerobic
• pyruvic acid (3-C) moves from the cytoplasm to
  the mitochondrial matrix
• Also known as oxidative decarboxylation

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Transition Reactions

• Pyruvic acid is broken down into CO2 and a 2-C
  acetyl group
• Joins with coenzyme A to become acetyl CoA
• Releases energetic electrons picked up by NAD
  taxi
• acetyl CoA drops the two carbons off at the Krebs
  cycle

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Krebs Cycle or Citric Acid Cycle

• Takes place in the mitochondrial matrix
• Composed of 9 rxns and 9 intermediate molecules
• Carbon atoms end up CO2
• 2 turns of the cycle for 1 glucose molecule

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Krebs Cycle

• 2 Cs from acetyl CoA are dropped off at the 4-C
  oxaloacetic bus
• 2 Cs plus bus forms 6-C citric acid
• C, energetic Hs, and O get dropped off at each
  stop until only the 4-C (oxaloacetic acid) bus
  remains for a new turn

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Krebs Cycle Totals

• 1 turn of the Krebs Cycle
• 1 ATP
• 3 NADH (from NAD)
• one FADH2 (from FAD)
• 2 CO2
• Double all figures for 2 turns of cycle

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Electron Transport Chain (ETC)

• Also called oxidative phosphorylation
• Occurs in the cristae (inner membrane) of the
  mitochondria
• High energy e-s are carried by their taxies
  (NADH and FADH2) to the ETC
• Oxygen is the final e- acceptor in the system

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End of the Electron Transport Chain

• Oxygen is the final electron acceptor
• At the end of the chain, the electrons and
  protons are captured by Oxygen
• 2 protons 2electrons 1 oxygen ???
• The final product of ETC is water (and 32 ATP)
• Without Oxygen, no new taxis, no aerobic
  respiration

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Electron Transport Chain

• Enzymes in the mitochondrial cristae pass the
  excited electrons
• As the electrons are passed, they lose energy in
  controlled bursts
• This energy is captured by ADP ATP

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Proton Pool

• Located between the inner and outer membrane of
  the mitochondria
• Excess H ions formed during respiration are
  concentrated here
• Charge imbalance is used to assist the ETC
  harness the electrons energy (just like
  photosynthesis!!!)
• The final step is ATP synthase

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Aerobic Respiration Totals
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Total ATP production

• 36 NET molecules of ATP are produced for every
  molecule of glucose
• 2 ATP from glycolysis
• 2 ATP from Krebs cycle
• 32 ATP from the ETC
• This captures 37 of the energy in glucose which
  is a high level of efficiency (where does the
  rest go?)

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Aerobic Respiration Totals
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Aerobic Respiration Totals
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Aerobic Respiration Totals
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Aerobic Respiration Totals
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Aerobic Respiration Totals
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What if there is no Oxygen?

• Anaerobic Respiration

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Anaerobic Respiration

• Also known as Fermentation
• Does not produce ATP
• Recycles NAD
• Two common types
• lactic acid (lactate)
• alcoholic

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Alcoholic Fermentation

• Converts pyruvic acid into ethyl alcohol
• CO2 is removed from pyruvate
• Two hydrogens are dropped off NADH2

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Alcoholic Fermentation

• Produces ethanol and carbon dioxide
• Only net 2 ATP produced (from glycolysis!)
• Used in making bread and beer

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Lactic Acid Fermentation

• Occurs in human anaerobic respiration
• Converts pyruvic acid into lactic acid
• Hydrogens from NADH are added to pyruvate

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Lactic Acid Fermentation

• Only net 2 ATP produced (from glycolysis!)
• Muscle goes into oxygen debt
• Later, when oxygen is present, Lactic Acid
  becomes pyruvic acid again, and enters the Krebs
  cycle

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Cellular Respiraton
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