Respiration?

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A Brief History of Respiration

• How cells get their ATP.
• There are three parts glycolysis, the Krebs
  cycle, and the electron transport chain.
• Total ATP count from all of these parts is about
  36.
• This is what respiration looks like if youre a
  chemistC6H1206 6O2 ? 6CO2 6H2O 36 ATP

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Glycolysis!

• Occurs in the cytoplasm and produces 2 net ATP
  (although it produces 4 ATP total)
• Six-carbon glucose is converted into two
  three-carbon pyruvates.
• Glucose Priming
• Phosphates from 2 ATP are added to the glucose,
  but this makes it unstable, so it breaks into 2
  G3P (a 3-carbon glucose/phosphate compound).
• Oxidation
• G3P are converted into pyruvate. G3P lose 2
  electrons and 1 proton each to NAD, which become
  NADH.
• G3P donate two phosphates to ADP, in a process
  called substrate level phosphorylation.
• ANIMATION!

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IMPORTANT QUESTION Do we have oxygen?

• If not, cells undergo fermentation.
• The 2 pyruvate from glycolysis accept H from
  NADH.
• In bacteria and yeast, this produces ethanol, and
  CO2 is released.
• In mammals, this produces lactic acid. Too much
  lactic acid pain.
• If so, pyruvate is oxidized and the Krebs cycle
  begins.

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Pyruvate Oxidation and the Krebs Cycle!

• Pyruvate Oxidation
• Occurs in the mitochondria.
• -1 C from pyruvate produces CO2 waste. New
  molecule is called acetyl, and another NAD
  becomes NADH.
• Acetyl coenzyme A Acetyl CoA.
• Krebs Cycle (citric acid cycle)
• Occurs in the matrix.
• 6CO2 waste, NADH and FADH2 electron carriers also
  produced.
• Happens twice per glucose molecule.
• ANIMATION!

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ETC!

• Also in the mitochondria, on the cristae.
• NADH and FADH2 produced in the Krebs Cycle are
  oxidized.
• Complexes containing heme lie across the folded
  membrane (they are transmembrane proteins) and
  pass electrons down from one complex to another.
• As the electrons travel down the chain this
  happens, the protons that had been connected to
  those electrons are pushed into the intermembrane
  space. The concentration there becomes great
  enough for chemiosmosis to occur.

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ETC!

• The protons go back into the matrix to achieve
  concentration equilibrium, but must pass through
  ATP synthase first. (This is facilitated
  diffusion.)
• Three protons are needed to create ATP. About 34
  molecules of ATP are created per molecule of
  glucose.
• The left over electrons join with oxygen and the
  protons to make H2O.
• Animation!