Question Video: Recalling the Net Production of ATP in Glycolysis Biology

What is the net yield of ATP for one glucose molecule undergoing glycolysis?


Video Transcript

What is the net yield of ATP for one glucose molecule undergoing glycolysis?

Glycolysis is the first stage of cellular respiration. Glycolysis takes place in the cytoplasm of cells of nearly all living organisms, and it happens whether oxygen is present or not. In glycolysis, a molecule of glucose undergoes a series of biochemical reactions to form two molecules of pyruvate or pyruvic acid. In the first set of reactions in glycolysis, two molecules of ATP are actually used to convert glucose into the phosphorylated sugar fructose-1,6-bisphosphate. So, currently, the yield of ATP is minus two.

Next, the six-carbon fructose-1,6-bisphosphate is split into two three-carbon compounds. This reaction does not use any ATP, but it also does not produce any ATP. So our current yield of ATP still stands at minus two. Finally, the two three-carbon compounds need to be converted into our final product, pyruvate. In this reaction, the three-carbon compounds donate a hydrogen ion and two electrons to a coenzyme called NAD+ to form reduced NAD or NADH. This reaction is coupled to another reaction.

Using the energy from the reduction of NAD+, G3P gains another phosphate group. This new compound doesn’t last long though. Following this, G3P loses both of its phosphate groups. These phosphate groups are gained by two molecules of ADP to form ATP. For each molecule of pyruvate formed, two molecules of ATP are produced. Because there are two molecules of pyruvate, four molecules of ATP are produced in total. So our yield of ATP before this stage was minus two, and here we have produced four molecules of ATP.

Now, we’re ready to calculate the net yield of ATP. Minus two ATP plus four ATP gives us a net yield of two ATP. So, for each single molecule of glucose that undergoes glycolysis, the net yield of ATP is two molecules.

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