Video narration
How does a cell turn food into usable energy from one glucose molecule? Glycolysis begins in the cytoplasm as a ten-step pathway. The cell first spends 2 ATP, investing energy to make glucose easier to split. Then the process flips: the split produces 4 ATP and 2 pyruvate. Subtract the 2 ATP spent, and the net gain is 2 ATP. So glycolysis works by investing energy first, then paying back more-ending with 2 ATP and 2 pyruvate.