In glycolysis, for each molecule of glucose that is oxidized to pyruvate, a net total of two molecules of ATP are produced. Here’s how it breaks down:
- ATP Used: During the initial steps of glycolysis, two molecules of ATP are consumed. This investment is necessary to help convert glucose into a more reactive form, ultimately breaking it down into two three-carbon molecules (glyceraldehyde-3-phosphate).
- ATP Produced: As the process continues, four molecules of ATP are generated through substrate-level phosphorylation during the later stages of glycolysis. This happens when these three-carbon molecules are converted into pyruvate.
When you consider the total ATP used (2 ATP) versus the total ATP produced (4 ATP), the net gain is:
Net Gain = ATP Produced – ATP Used = 4 ATP – 2 ATP = 2 ATP
So, to summarize, glycolysis results in a net production of two ATP molecules for every molecule of glucose that is converted to pyruvate.