I believe "substrate level Phos. only" = the direct phosphorolation of ADP -> ATP vs the coupled reactions of NADH and FADH2 we have in e- transport chain which oxidises NADH and FADH2 to create a proton gradient, that gradient drives the ADP ----> ATP phosphorlation (oxidative phos.).
So the two substrate only reactions where ADP is directly phosphorolated to give a NET of ATP are:
Glycolysis (cytosol): which yields a net 2 ATP/1 Glucose molecule (note that this substrate level phos. happens several times here but only yields a "net" of 2 ATP)
Krebs Cycle (Mit. Matrix): net 2 ATP (1 per cycle actually in the form of GTP which transfers its Pi to ADP --> ATP)
So a net of only 4 ATP from substrate level phosphorolation.
All the other ATPs are generated through oxidative phosphorolation in the e- transport chain by taking the reduced NADH and FADH2 molecules from Glycolysis (2 NADH), PDC (2 NADH), Krebs (6 NADH, 2FADH2), and oxidizing them pumping protons OUT of the Mit. matrix (increasing pH in the matrix) into the inner mit. membrane. This gradiant (with mit. membrane proteins) then drives the phosphorolation of ATP production. This is where the bulk of ATP comes from.
Ok after a few edits I think I got this right, I just covered it yesterday so it was fresh on my mind. Feel free to add any info.
Also I dont know what to do for reading either, I am the slowest test taker there is. I spent 8 hours on an O-Chem test one time when the class avg. was 2.5. The few undergrad classes that had timed tests were always the toughest, instead of an A-, B+ student I was dropped to a B- student. My g-chem class for example, I was #1 in my class of 72 all semester until the final which was 25 questions and a 2 hour limit. I missed the last 6 questions b/c I didn't finish :-( dropping my A- to a B (not even a B+).
This is why I have put off the dat for so long, I should have taken it and applied last year or earlier. I am studying 12-16 hrs/day right now but my battle in EVERY section by far is time. My brain just doesn't function well under time constraints, I don't know if it is my ADD or what but, I can't even reason well and answer stuff that I know sometimes, so I sympathise with you as I am in the same boat, or worse. My test date is Oct. 1 (24 days away) so I am just trying to do as many practice tests as possible etc.
