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7/31/2019 Cellular Respiration-May 3
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Chapter 9:
Cellular RespirationHarvesting
Chemical Energy
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O
xidationand
Re
duc
tion
Oxidation is the Loss of Electrons
E.g., something that is oxidized in the course of a
chemical reaction with Oxygen has had electronsstolenby Oxygen
Reduction is the Gain of Elections
E.g., a gain of electrons results in a decrease(reduction) in electrical charge (since electrons carry
a negative charge)
Metal ores are Reduced to metals (via the addition
of electrons)metals found in ores are in an oxidized
form relative to metals found as metals
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ATP Genesis in Eukaryotes
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Glycoslysis
Glycolysis feeds material toelectron transport chains plus
makes ATP in its own right
Note in eukartyotic cellsthat glycolysis takes
place in the cytoplasm,i.e., outside of the
mitochondria
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Glucose P
P
Glyceraldehyde
3-phosphate (x2)
PP
Pi
ATP
ADP
ATP
ADP
+ NAD+
+ NADH + H+ (2x)
ATP(2x)
ATP(2x)
1,3-biphosphoglycerate
(2x)
cellular respirationor fermentation
cellular respiration
or fermentation
Fructose
1,6-biphosphate
Pyruvate (x2)
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Step
so
fG
lyco
lys
is First priming
ATP
Phosphorylatedhexose
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Step
so
fG
lyco
lys
is
Secondpriming ATP
Isomerizationstep
BiphosphorylatedHexose
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Step
so
fG
lyco
lys
is
Sugar-splitting(glyo-lysis) step Phosphorylated
trioses
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Step
so
fG
lyco
lys
isThis reaction is driven to the right bythe removal of reactant to the right
Note that these are phosphorylatedversions of the two simplest sugars
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Step
so
fG
lyco
lys
is
Noteinorganic
phosphate
This iswhere
NAD+ isrequired
Note that stoichiometry istwo of these reactionpathways per starting
glucose (hence the 2s)
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Glyceraldehyde-3-Phosphate Dehydrogenase
enzyme
substrates
products
Have to have NAD+for glycolysis to work
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Step
so
fG
lyco
lys
is
First ATPsproduced (2)
This is asubstrate-levelphosphorylation
step
Movement ofphosphate
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Step
so
fG
lyco
lys
is
Second ATPsproduced (2)
Increase in
electron densitynear phosphate
Three-carbonproduct
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Into the Mitochondria
Oxidation ofpyruvate step
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Oxidation of Pyruvate
Production of
first CO2
2nd
and 3rd
NADH
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Removal of Rest of CO2s and Energy
Krebs cycleconverts
remainingcarbons (2 x 2)
to CO2s
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Ou
tlin
eo
fKre
bs
Cyc
le
Note that thereare 2 AcetylCoAs per
glucose so 2turns perglucose
Substrate-levelphosphorylation
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Kre
bs
Cycle
inDe
tail
Note acetyl CoA
Note citric acid
Noteconversion of
carboxylgroups to
CO2
Noteformation of
FADH2
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Electron Transport & Oxidative Phosphorylation
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Elec
tron
Trans
port
Sy
stem
Note differentlocations ofaddition of
electrons
Note additionof both
electrons and
protons tooxygen
Not shown isproton
pumping!
Series of
redoxreactions
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ATP Bookkeeping
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ATP
Book
keepin
g
One glucose yields:
2 ATP in glycolysis
2 NADH in glycolysis
2 NADH as pyruvate enters citric acid cycle
2 ATP in citric acid cycle
6 NADH in citric acid cycle 2 FADH2 in citric acid cycle
Thats 2 + 6 2 + 6 + 2 + 18 + 4 = 36
The 2 is an NADH transportation into the
mitochondria cost
Thats 2 + 6 0 + 6 + 2 + 18 + 4 = 38 in bacteria(where cytosol and inside of mitochondrium are
equivalent)
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Anaerobic Respiration
employs an
inorganicmolecule otherthan O2 as a
terminal electronacceptor.
Less ATP is
produced becausethese electron
acceptors requiremore energetic
electrons
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F
ermen
tation
Alternativemeans of NAD+
regeneration
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ac
ticA
cidFe
rmenta
tion
To glycolysis