Number of ATP per glucose?

[Little Etoile]

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Pg. 22 of my book:



Formula for glycolysis says:

glucose + 2 ADP + 2 Pi + 2 NAD+ --> 2 pyruvate + 2ATP + 2 NADH + 2 H20 + 2 H+

But below, says, “…this is split into two 3-carbon units that are oxidized to pyruvate, producing 2 ATP and 1 NADH per pyruvate, or 4 ATP and 2 NADH per glucose.






Can someone explain this discrepancy? I think I am missing something here. Is it two ATP or four?



As always, thanks in advance.

 

[sleepy425]

Pg. 22 of my book:



Formula for glycolysis says:

glucose + 2 ADP + 2 Pi + 2 NAD+ --> 2 pyruvate + 2ATP + 2 NADH + 2 H20 + 2 H+

But below, says, “…this is split into two 3-carbon units that are oxidized to pyruvate, producing 2 ATP and 1 NADH per pyruvate, or 4 ATP and 2 NADH per glucose.


Can someone explain this discrepancy? I think I am missing something here. Is it two ATP or four?



As always, thanks in advance.

The process uses up two molecules of ATP to convert glucose to fructose-1,6-bisphosphate, which is then split into two 3-carbon units. those two units are each oxidized to pyruvate to give 2 ATP and 1 NADH per 3-carbon unit. so it's 4 ATP and 2 NADH per glucose that's formed. Then you take away two ATPs because you used them in the beginning. So the net formation is 2 ATP and 2NADH, because you used 2 and made 4 ATP.