Oxidation and Reduction in Cellular Respiration

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Oxidation and Reduction in Cellular Respiration
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• cellular metabolism
• the total of all reactions that use or release
  energy in a cell
• anabolism and catabolism

• synthesis
• anabolism
• energy is stored
• energy must be put in
• uses up ATP

raw materials H2O, CO2, O2, etc
large/complex molecules sugar, protein,
carbohydrates, etc

• decomposition
• catabolism
• energy is released
• energy becomes available for other things
• produces ATP

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Cellular respiration overview
glucose
glycolysis
2 pyruvate
if oxygen (aerobic respiration)
if NO oxygen (ANaerobic respiration)
yeast alcohol CO2
Krebs cycle
bacteria vinegar
bacteria and muscles lactic acid
ETS
AEROBIC RESPIRATION (38 ATP produced)
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Oxidation and reduction

• Reduction
• when a molecule
• loses oxygen
• gains hydrogen
• gains electron(s)
• this tends to be a GAINING of stored energy for
  that molecule
• the molecule receives energy
• GER
• Gain Electrons Reduced

• Oxidation
• when a molecule
• gains oxygen
• loses hydrogen
• loses electron(s)
• this tends to be a LOSS of stored energy for that
  molecule
• the molecule gives off energy
• LEO
• Lose Electrons Oxidized

If one molecule gets OXIDIZED, then some other
molecule gets REDUCED.
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Oxidation and Reduction

• remember that electrons (e-) are about 1/2000 the
  mass of a proton
• chemical reactions often occur BECAUSE an
  electron has traded places between two
  molecules
• the molecule that is the DONOR of the electron is
  the one that gets oxidized (because that molecule
  LOSES an e-) (L.E.O.)
• the molecule that GAINS that electron is
  therefore REDUCED (G.E.R.)

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Oxidation and Reduction

• if a molecule or atom gains oxygen, that
  molecule is OXIDIZED.
• iron oxygen --------------gt rust
• Fe O2 --------------------gt Fe2O3
• in this equation, Fe (iron) is the atom or
  molecule of interest
• Fe GAINS oxygen, therefore Fe is OXIDIZED.

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Oxidation and Reduction

• another example
• C6H12O6 O2 -----------------gt CO2 H2O ATP
• the Carbon is the element of interest here
• Carbon has oxygen added to it
• therfore carbon is oxidized in this reaction
• if something gets oxidized, something else must
  get reduced in the process...

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Oxidation and Reduction

• C6H12O6 O2 -----------------gt CO2 H2O ATP
• we saw that carbon was oxidized to produce CO2.
• in the process, the OXYGEN had hydrogens added to
  it.
• therefore oxygen was REDUCED, and the product is
  H2O
• so carbon was oxidized, and oxygen was reduced.

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oxidation and reduction

• in cellular respiration, oxygen and water play
  important roles.

H2O
O2

H
the balanced equation looks like this
H2O
2
O2

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H
textbooks will often write this divided by 2...
H2O
1/2
O2

2
H
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oxidation and reduction
H2O
O2

H

• focus on oxygen in this case, O has H added to
  it
• therefore O is reduced
• and the product is water.

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oxidation and reduction
H2O
O2

H

• focus on hydrogen in this case, H has O added
  to it
• therefore H is oxidized
• and the product is water.

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oxidation and reduction

• this reaction happens in both directions in
  cells.

O2

H
H2O

• H (in water) has oxygen REMOVED from it
• therefore H is reduced

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oxidation and reduction

• if one substance is OXIDIZED in a reaction, some
  other substance must be REDUCED.

oxygen is reduced to make the product
H2O
O2

H
hydrogen is oxidized to make the product
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NAD
NADH
e-
oxaloacetate
malate
in the Krebs cycle, malate is changed into
oxaloacetate in the process, one NADH (high
energy) molecule is created.
malate gives an e- to NAD
therefore NAD is REDUCED (G.E.R)
and malate is OXIDIZED (L.E.O)
then malate rearranges to form oxaloacetate