ATP question


How many ATP are gained from substrate level phosphorylation?

this is from the krebs cycle i believe.. my book says 1 but wikipedia says 4.. so im confused

How many ATP are gained from oxidative phosphorylation?

can someone help me? thanks in advance


6 Posts

My Human Bio text says that 4 ATP are gained from substrate level phosphorylation during glycolysis but they are used up during cellular respiration (2 to initiate glycolysis and 2 to shuttle electrons) Then 2 ATP are gained by substrate level phosphorylation during the Krebs cycle and 34 ATP are gained by oxidative phosphorylation during the electron transport system for a total of about 36 ATP. Hope that helps! :D


2 Posts

From each glucose molecule processed the cell gains 36 ATP. Glycolysis releases two by substrate level phosphorylation. However, glycolysis also releases hydrogen to NAD making it NADH which during the electron transport system creates 4 more ATP by oxidative phosphorylation. The krebs cycle (two revolutions) creates 2 by substrate level phosphorylation in the form of GTP. However, during the krebs, hydrogen is released to NAD and FAD making them NADH2 and FADH. These then travel to the electron transport chain and create 28 ATP through oxidative phosphorylation. NADH = 24 while FADH=4. Does this make sense?

4 through substrate level (2 in glycolysis and 2 in krebs)

32 through oxidative (4 from NADH produced through glycolysis, 24 through NADH in TCA/krebs cycle, and 2 from FADH2 produced in TCA/krebs cylce)

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