Dec 14, 2009
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Q. In regard to catabolic reactions, all of the following statements describe the purpose and significance of the citri acid cycle excepts:
a) The cycle produces reducing equivalents in the form of NADH and FADH2, for use by the ETC
b) Citric acid cycle operates in Oxidative mode.
c) Oxidation of citric acid cycle intermediate requires the presence of oxygen
d) The cycle is the main metabolic produce of CO2
e) all of the above.
 

MrBeans

MrBeans
Nov 6, 2009
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Is the answer c?

ETC requires O2, not the TCA cycle.

TCA cycle produces CO2
TCA cycle makes NADH and FADH2 for ETC
Oxidation occurs in the TCA cycle

So, I would guess the answer to be c.
 

Maygyver

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Jun 14, 2008
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Is the answer c?

ETC requires O2, not the TCA cycle.

TCA cycle produces CO2
TCA cycle makes NADH and FADH2 for ETC
Oxidation occurs in the TCA cycle

So, I would guess the answer to be c.
I concur.
 

MrBeans

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If O2 was not present, fermentation would kick in to turn the NADH back into NAD+ for glycolysis.
 
Jan 24, 2010
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This is tricky because krebs cycle and electron transport chain can't run anarobically, which means that they need to occur under the presenc eof oxygen. BUT LIKE undergradguy said oxygen is needed in an indirect way. It's not one of the actual reactants in the krebs cycle.
 

akeurogh

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Jun 22, 2009
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Even though O2 is needed for the TCA cycle to occur, O2 is not the oxidizing agent in the TCA cycle. The oxidizing agent in the TCA cycle would be NAD+. Therefore the answer would be C.

O2 as an oxidizing agent occurs in the ETC.