During the second half of glycolysis, ATP and NADH are produced as the three‑carbon sugars are oxidized and converted into pyruvate.

Quick Scoop: What Happens in the Second Half of Glycolysis?

Think of glycolysis as having two halves:

  • First half: energy-investment phase (cell spends ATP).
  • Second half: energy-payoff phase (cell makes ATP and NADH).

During the second half (energy‑releasing/payoff phase):

  1. The two three‑carbon molecules (glyceraldehyde‑3‑phosphate, from splitting glucose) are oxidized and phosphorylated.
  2. NAD⁺ is reduced to NADH , capturing high‑energy electrons.
  3. ATP is generated by substrate‑level phosphorylation :
    • 4 ATP are formed in this phase per original glucose.
    • Since 2 ATP were used in the first half, the net gain is 2 ATP per glucose.
  4. The pathway ends with the formation of two molecules of pyruvate from the original one molecule of glucose.

So in most multiple‑choice formats, the correct idea is:

During the second half of glycolysis, ATP is made and NADH is produced as glyceraldehyde‑3‑phosphate is converted to pyruvate.