abrar
Forum Newbie
Topics: 1
Posts: 11
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hi,
could someone help me regarding some concept i cannot understand.
during glucose metabolism in aerobic pathway,a total of 38(or36)ATP molecules are generated depending on whether the malate or glycerol-3-P shuttle are used to enter into ETC.
In glycolysis,2ATPs are generated and 2NADH(which can enter oxidative phosphorylation by either malate or glycerol-3-P shuttle resulting in 3 or 2 ATP molecules respectively).So a total of 8 or 6 ATPs are produced.
In TCA cycle,each time an acetyl CoA runs through the cycle,3 NADH,1 FADH2 and 1 GTP are produced leading to a total=12 nucleosideTPs.so a total of 24ATPs as 2 acetyl CoA are produced per molecule of glucose.
Adding up the total ATPs from glycolysis and TCA cycle brings the total to24+8=32.where do the 6 extra ATP molecules come from,to take the total to 38?i read the topic well but couldnt figure out.i'd appreciate if someone could help me out.
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| Idiopathic
Forum Guru
Topics: 19
Posts: 641
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your initial numbers are off...you get 30 net ATP's with the glycerol-P shuttle and 32 with the malate-aspartate shuttle.
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| crista
Forum Guru
Topics: 121
Posts: 408
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when you transform pyruvate in acetyl coA, you obtain another NADH;becose you have 2 pyruvate from 1glucose---2*3=6
32+6
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| Idiopathic
Forum Guru
Topics: 19
Posts: 641
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How many ATPs?
It is tempting to try to view the synthesis of ATP as a simple matter of stoichiometry (the fixed ratios of reactants to products in a chemical reaction). But (with 3 exceptions) it is not.
Most of the ATP is generated by the proton gradient that develops across the inner mitochondrial membrane. The number of protons pumped out as electrons drop from NADH through the respiratory chain to oxygen is theoretically large enough to generate, as they return through ATP synthase, 3 ATPs per electron pair (but only 2 ATPs for each pair donated by FADH2).
With 12 pairs of electrons removed from each glucose molecule,
10 by NAD+ (so 10x3=30); and
2 by FADH2 (so 2x2=4),
this could generate 34 ATPs.
Add to this the 4 ATPs that are generated by the 3 exceptions and one arrives at 38.
But
The energy stored in the proton gradient is used for a number of other mitochondrial functions such as the active transport of a variety of essential molecules and ions through the mitochondrial membranes.
NADH is also used as reducing agent for many cellular reactions.
So the actual yield of ATP as mitochondria respire varies with conditions. It probably seldom exceeds 30.
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| abrar
Forum Newbie
Topics: 1
Posts: 11
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thanx to all of you!!!
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| abrar
Forum Newbie
Topics: 1
Posts: 11
|
thanx to all of you!!!
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