Which glycolytic enzyme catalyzes the cleavage of fructose-1,6-diphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate?

• A. aldolase
• B. phosphofructokinase
• C. pyruvate kinase
• D. glucose-6-phosphate dehydrogenase

Answer: (A)

Cleavage of a six-carbon fructose-1,6-bisphosphate into two three-carbon units is performed by aldolase. It splits fructose-1,6-bisphosphate into dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P). In glycolysis, DHAP is quickly converted to another molecule of G3P by triose phosphate isomerase, so both products proceed through the pathway as G3P for the later steps that generate ATP and NADH. The other enzymes listed act at different points: phosphofructokinase starts the commitment step by forming fructose-1,6-bisphosphate, pyruvate kinase drives the final ATP-yielding step from phosphoenolpyruvate to pyruvate, and glucose-6-phosphate dehydrogenase is part of the pentose phosphate pathway, not glycolysis.