Hey guys,

I am a little bit confused on how to calculate the number of ATP generated in a certain pathway.

The books say:

• Anaerobic glycolysis yields 2ATP/glucose by substrate-level phosphorylation.
• Aerobic glycolysis yields 2ATP/glucose plus 2NADH/glucose
• 2 Shuttles that can form ATP are;
  • Malate: 8ATP/glucose
  • Glycerol phosphate: 6ATP/glucose

Where are the ATPs comming from? I thought it had something to do with reoxidization of NADH to NAD and FADH2 to FAD.

I believe there might be a concept behind this which I do not understand. Also how would I calculate ATPs from another cycle if asked to do that?

the atp is generated by two methods in our body, one is oxidative phosphorylation which uses energy from reduction of NADH and FADH2, this is the major supply n for every NADH we make 3ATPS n FADH2 makes 2ATPS in ETC.NADH n FADH2 are produced in cytoplasm n to get into mitochondria under aerobic conditions need shuttle service.malate shuttle relys on NADH n G3P on FADH2 the no. of ATPs produced with both is different, malate n G3p shuttles are not electron transport chain but merily shuttles used to transport NADH n FADH2 energy across mitochondrial membrane. which then are used in the ETC.
second method of ATP production is susbstrate-level phosphorylation which produces ATP directly from ADP but is low yeild as only 2 ATPS/glucose.this happens in glycolysis.in aerobic condition, glycolysis will proceed to TCA n Oxidative phosphorylation which will produce the major bulk of ATPs.
glycolysis=2ATP/glucose+(1NADH)x2 for every glucose
now if NADH uses malate shuttle it will produce 3ATPs n with G3P only 2.so total glycolysis ATPs under aerobic conditions ATP can be either 8 with malate or 6 with G3P.obviously these shuttles are needed only under aerobic conditions, anaerobically substrate level phosphorylation is the only source.
so glycolysis=8ATP
now pyruvate produces NADH while converting to acetyl coA n each glucose gives 2 pyruvate so 2 NADH=6ATP
TCA=3NADH(3ATP/NADH)+1FADH2(2ATP/FADH2)+1GTP which means
(3x3+2+1GTP)X2 for everything per glucose.as TCA deals WITH three C n glucose gives two Acetyle CoA so evrything doubles up in TCA.
so TCA=24
so 8+6+24=38ATP
this calculation has been done assuming that every molecule of NADH will use malate shuttle to enter mitochondria.