Photosynthesis and respiration question

[ozzie33]

I am having some trouble with this question from Kaplan:

Which of the following is true with regard to photosynthesis and respiration?
A. NADH produced in the dark reactions directly supplies energy for the synthesis of sugars
B. NADH molecules produced during glycolysis yield 3 ATP during oxidative phosphorylation
C. CO2 is fixed in the light reactions of photosynthesis
D. Oxidative phosphorylation takes place across the inner mitochondrial membrane
E. FADH2 yields 3 ATP during oxidative phosphorylation




Now they say that the answer is d, but I am positive we learned in biochem that each molecule of NADH is worth 3 ATP in the ETC *and the same is in campbell. IS this just a bad question or am I missing out on some small detail. here

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[Ryltar]

NADH = 3 ATP, FADH2 = 2 ATP, and NADH produced in glycolysis = 2ATP. CO2 is fixed in dark reactions. NADH is produced in light reactions. Oxidative phosphorylation does take place across the inner mitochondrial membrane, so D.

 

[Ryltar]

The key here is only NADH from glycolysis is equal to 2ATP. NADH from anywhere else is equal to 3ATP.

 

[peyman2002]

also take note that NADPH is produced not NADH

 

[ozzie33]

thanks alot, thats what I was thinking but didn't know for sure

 

[BrooklynZoo1184]

You guys are pretty much right, and that's how some biology outlines will explain it. In a more detailed text, you will find a slight variation though.

NADH always produces 3 ATP, even in Glycolysis. However, only 2 of the 3 ATP produced make it to the final product. This is because each NADH spends 1 ATP on transportation into the mitochondrial matrix.

You multiply what I just said by 2 (for each glucose molecule), and that's a total of 2 NADH molecules, 6 ATP total, and only 4 ATP net.

Why did I bother to add this extra information?

The statement could be phrased differently.

Instead of saying "NADH molecules produced during glycolysis yield 3 ATP during oxidative phosphorylation", which is false, it could say "NADH molecules produced during glycolysis yield 3 ATP during glycolysis", which is true.

Can anyone confirm that I'm not totally off base here?

 

[Ryltar]

Thanks for the clarification. I'll add that to my study notes!

 

[Ryltar]

Only 2 ATP per NADH since the coenzyme must feed into the electron transport chain from the cytoplasm rather than the mitochondrial matrix.

 

[khakwanit1]

NADH produced during glycolysis only gives 2 ATP because it loses one electron while entering mitochondrial membrane (requires energy-active transport)."NADH molecules produced during glycolysis yield 3 ATP during glycolysis", which is true." This is still not true because NADH doesn't produce ATP during glycolysis. Oxidative phosphorylation takes place in electron transport chain and ATP's are produced by ATP synthase. Therefore, NADH is only used in mitochondria for energy. You don't need to know how the electrons work throughout this process. Hope this helped....

 

[Sublimation]

I am having some trouble with this question from Kaplan:

Which of the following is true(look for the true statement) with regard to photosynthesis and respiration?
A. NADH produced in the dark reactions directly supplies energy for the synthesis of sugars NO IT DOES NOT.
B. NADH molecules produced during glycolysis yield 3 ATP during oxidative phosphorylation. oxidative phosphorylation makes a **** load of atp
C. CO2 is fixed in the light reactions of photosynthesis. wrong
D. Oxidative phosphorylation takes place across the inner mitochondrial membrane. THIS IS TRU AND OBVIOUS AND EASY!!!! i think everyone is overcomplicating this.
E. FADH2 yields 3 ATP during oxidative phosphorylation




Now they say that the answer is d, but I am positive we learned in biochem that each molecule of NADH is worth 3 ATP in the ETC *and the same is in campbell. IS this just a bad question or am I missing out on some small detail. here no my friend u are right...yes oxidizing NADH will give u that....but keep in mind ETC makes a ****load of atp...it just uses an proton gradiant....i would go into mroe detail on this just pm me and ill send u a good power point on this.

response in bold

 

[Audball]

Can anyone tell me (in a practical involving electron transport chain), why is the rate of oxygen consumption greater when succinate (FADH) is substrare than when malate/glutamate (NADH) is substrate?
I know that FADH makes less ATP than NADH

This is obviusly because oxygen consumption is slower in the NADH pathway, but why is this?


Help is much appreciates, have my 1st medical year exams in a few weeks!

Aud