how many ATP are produced by the electron transport chain

[hoyas19]

I thought I had this down but now I'm confused. I know that eukaryotic cells make 36 ATP during respiration and prokaryotes makes 38 ATP. If 2 ATP are formed during glycolysis, 2 are used during pyruvate decarboxylation, and 2 are formed during the krebs cycle, shouldn't 32 be formed during the ETC for a total of 36? Why does kaplan say 34 are made in the ETC?

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[Andre3k]

Glycolysis
4 made - 2 used= 2 ATP substrate level
2 NADH x 2= 4 ATP (enters at complex II)

Pyruvate Decarboxylation
1 NADH x two pyruvate= 2 NADH x 3= 6 ATP

Krebs Cycle
3 NADH x two pyruvate= 6 x 3= 18 ATP
1 GTP x two pyruvate= 2 GTP= 2 ATP
1 FADH2 x two pyruvate= 2 FADH2 x2= 4 ATP

Total: 2+4+6+18+2+4= 36 ATP

 

[Andre3k]

4 ATP substrate level
32 ATP electron transport chain

In prokaryotes the NADH from glycolysis dont have to cross a mitochondrial membrane so you get all the ATP youre supposed to get for them.
2 x 3= 6 NADH from glycolysis and gives you 2 more ATP to equal 38.

 

[doc3232]

Not to confuse even more, but some books say only 2.5 ATP are made from NADH and 1.5 ATP from FADH2...I think Princeton does this.

 

[eminent1217]

I thought I had this down but now I'm confused. I know that eukaryotic cells make 36 ATP during respiration and prokaryotes makes 38 ATP. If 2 ATP are formed during glycolysis, 2 are used during pyruvate decarboxylation, and 2 are formed during the krebs cycle, shouldn't 32 be formed during the ETC for a total of 36? Why does kaplan say 34 are made in the ETC?

Ok... in cellular respiration there are total number of 36 ATP would generated in eukaryote and 38 atp for prokaryote.

First of all, the reason of 2 atp difference b/w eukaryote and prokaryote is presence of mitochondria. Since the kreb cycle is happening in mitochondria, 2 out of 4 atp generated from glocolysis will used to get into the membrane of mitochondria, which is active transport. This is why we regard only 2 atp has generated from glycolysis. (start with 2atp--> 1 glucose became 2NADH--> 3atp/NADH, so 6 atp will generated --> 6 atp - 2atp initially inputted = 4 atp, and out of 4 atp, 2atp would used in active transport in order to get into the membrane of mitochondria. So, finally we left with only 2 atp.) Since, prokaryote does not have mitochondria, and respiration is not happening in mitochondria, thats why they dont have to use 2 atp from glycolisis. So, they will remain with 4 atp from glycolisis.

After the glycolisis, the Kreb cycle (also called citric acid cyle held in matrix,) will happen, and it generate 2 more atp.

Finally, 32 atp would generated from oxidative phospolylation.

so,,, 2+2+32 --> 36 for eu, 4+2+32 --> 38 for pro.

I just checked with kap bb and lesson book, they also saide 36, 38.

 

[docgen]

Please don't mind. I kinda confused and cellular respiration gave me the most difficult time studying it. what are the differences between substrate level phosphorylation and oxidative phosphorylation? i'm afraid somebody will say why i ask suck a basic, stupid question or why i don't get it

 

[Sea of ASH]

Not to confuse even more, but some books say only 2.5 ATP are made from NADH and 1.5 ATP from FADH2...I think Princeton does this.

ya ur right princeton says that,

what you got to keep in mind is that these are all estimations and its not set in stone. for the DAT i think it would be safe to go with kaplan. 36 for eukaryotes and 38 for pro

 

[Andre3k]

Please don't mind. I kinda confused and cellular respiration gave me the most difficult time studying it. what are the differences between substrate level phosphorylation and oxidative phosphorylation? i'm afraid somebody will say why i ask suck a basic, stupid question or why i don't get it

Substrate Level- ATP made directly from Glycolysis (2) or Krebs Cycle(2)

Oxidative Level- ATP made from NADH or FADH2 in the ETC

 

[Andreas]

Also, Pyruvate uses 1 ATP in order to cross the mitochondrial membrane. 2 pyruvate molecules = - 2 ATP. Therefore 36 ATP - 2 ATP = 34 ATP.

 

[Jo Calihan]

I thought I would update this, since there still isn't a correct answer posted for this question:

During glycolysis, 2 NET ATP are produced. 2 NADH are produced.
During the PDH reaction, two Ac-CoA are produced, along with 2 NADH.
For the two Ac-CoA molecules that enter the TCA Cycle there will be 2 GTP (converted to ATP), 6 NADH, and 2 FADH2 produced.

--- So far we have 4 ATP, 10 NADH (33.3), and 2 FADH2 (4)

NADH enters ETS through complex I, which pumps 4 protons into the IM space. Complex III pumps 2 protons, and complex IV pumps 4 protons. For each NADH that enters ETS, there will be 10 protons pumped into the IM space. We have 10 NADHs, and therefore 100 protons in the IM space. ATP synthase synthesizes 1 ATP per 3 protons that pass through it back into the matrix. So we have 33.3 ATP produced from NADH

--- So far we have 4 ATP from glycolysis and TCA, and 33.3 ATP from NADH. Combining these amounts gives us 37.3 ATP

FADH2 enters ETS through complex II (also called succinate DH), which does not pump protons into the IM space. The 2 FADH2 produced equal 6 protons in the IM space. * Two fewer because it missed out on complex I. There are 12 protons in the IM space as a result of FADH2's oxidation. Again, 1ATP will be produced for every 3 protons proton passing through the ATPase. So because there are 2FADH2, we have 12 protons, and thus 4 ATP are produced from FADH2

---So far we have 37.3 ATP as a result of Glycolysis, TCA, and protons from NADH. Combing this to the 4 produced from FADH2 gives us 41.3 ATP produced per molecule of glucose.

So.. why do textbooks say that there are 32 produced and not 41.3?

Pi needs to be transported into the matrix, which requires a proton to accomplish. Also, two other contributing factors are that the only point which protons can exit is the ATPase (some miss the bus because they are hanging out elsewhere), and some leak out of the F0 subunit.

If we now take the transport of Pi into consideration, it takes 4 protons to synthesize 1 ATP molecule. We divide the total number of protons from NADH (100) and FADH2 (12) (=112) to get 28 ATP produced. When we add the 4 ATP produced as a result of glycolysis and TCA, we get 32 ATP produced per molecule of glucose.

 

[drblackwolf]

Not to add even more confusion, but I've read that these numbers are more theoretical yields than what the cell actually produces during respiration. Yes, in a perfectly functioning system the numbers are supposed to be 36 ATP for eurkaryotes and 38 for prokaryotes but in reality they aren't operating at 100% efficiency

 

[ead1993]

HI, sorry to re-open this convo, but I'm super struggling with this currently and I'm not sure anyone has really reached a conclusion as to what's going on? Is princeton the only book (and my own textbooks from biochemistry) that uses 32 and 34 ATP? is this from counting FADH2 as 1.5 rather than 2.5 ATP? or is there some other consideration that I'm missing? I've gone through the calculations like tons of times and memorized the paths this way but most sources are saying 36 and 38 ATP now. Idk. Halp plz