10'4 Many substances must pass the mitochondrial inner membrane'

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10.4 Many substances must pass the mitochondrial
inner membrane. Assuming all energy is provided
by glucose, how many of the following molecules
will move and in which direction per molecule of
glucose? A) pyruvate-- 2 in B) oxygen-- 6 in C)
ATP-- lots out (around 35-) D) ADP-- lots in
(same as ATP) E) acetyl CoA-- none (pyruvate to
acetyl CoA occurs in matrix) F) glycerol
3-phosphate-- none (cytoplasm) G) NADH-- none/2
in (2 made in glycolysis, but transfers
weirdly) H) FADH2-- none (all in matrix) I)
oxaloacetate-- none (full cycle) J) water-- lots
out (6 from glucose 1 per ATP generated) K)
electrons-- 2 in /none (weird transfer of NADH
from glycolysis) L) protons-- none (move in and
out to generate energy, otherwise lost)
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10.6 use table 10.2 (reduction potential table)
to calculate A) Can isocitrate pass electrons
to NAD exergonically under standard conditions? Y
es, as isocitrate reduction is more negative than
NAD reduction. B) what is the DE0' for the
oxidation of isocitrate to NAD under standard
conditions? DE0' electron acceptor - electron
donor DE0' -0.32V - (-0.38V) 0.06V, so
electrons will move this direction spontaneously
C) calculate DG for the reaction under standard
conditions DG0' -nFDE0' DG0' -223,0620.06
-2767 cal/mol important as a step in TCA cycle
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10.6 cont. D) what is the DE0' and DG for the
oxidation of lactate to pyruvate by NAD? DE0'
electron acceptor - electron donor DE0' -0.32V
- (-0.19V) -0.13V, so electrons will NOT move
this direction spontaneously DG0'
-nFDE0' DG0' -223,062(-0.13) 5996 cal/mol
This value is important because lactate must be
regenerated after anaerobic metabolism in certain
tissues. Can't occur in std. conditions! E)
what is the DE0' and DG for the oxidation of
succinate to fumarate by NAD? DE0' electron
acceptor - electron donor DE0' -0.32V -
(-0.03V) -0.29V, so electrons will NOT move
this direction spontaneously DG0'
-nFDE0' DG0' -223,062(-0.29) 13336
cal/mol this is very positive and not likely to
occur in the cell under any conditions
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10.6 cont. F) what is the DE0' and DG for the
oxidation of succinate to fumarate by coenzyme
Q? DE0' electron acceptor - electron donor DE0'
0.04V - (-0.03V) 0.07V, so electrons will
move in this direction spontaneously DG0'
-nFDE0' DG0' -223,062(0.07) -3229 cal/mol
so this reaction will proceed FAD is involved,
but as it immediately passes its electrons to coQ
as part of the complex, coenzyme Q is the actual
electron acceptor in this step