oh boy 40 ATPs for Prokaryotes

ok coming back to your question ....

In Glycolysis, there is net gain of

**2 ATPs, + 2 NADH **
Pyruvate Decarboxylation yields 1 NADH for each pyruvate molecule. We have 2 pyruvates from Glycolysis, therefore,

**2 NADH** gain from here .

Now we move to Kreb Cycle , for each pyruvate you get 1 ATP, 3 NADH, 1 FADH2 (the way i remember it is 1:3:1 ) . We have 2 pyruvates, therefore its going to be....

**2 ATPs , 6 NADH , 2 FADH2 **
now comes the Electron Tranport .... where each NADH produces 3 ATP, and each FADH2 produces 2 ATPs ....

The most important thing to remember here is that the 2 NADHs we got from Glycolysis DONT enter mitochondria and dont participate in ETC, therefore they yield 2 ATP each and not 3
Now if u calculate the TOTAL ATPs .... you get 36

* 2 ATP - Glysolysis

* 4 ATP - from 2 NADH produced by glycolysis

* 6 ATP - from pyruvate decarboxylation

* 2 ATP, 18 ATP (from 6 NADH), 4 ATP (from 2 FADH2) - Kreb Cycle

Hope this helped