Q.37 During glycolysis, conversion of 1 mole of fructose 1,6-bisphosphate
to 2 moles of pyruvate leads to the formation of:

1. 2 moles of NADH and 4 moles of ATP
2. 1 mole of NADH and 1 mole of ATP
3. 2 moles of NADH and 2 moles of ATP
   1. 2 moles of NADH and 2.5 moles of ATP

      Correct Answer: 2 moles of NADH and 2 moles of ATP

      Glycolysis from fructose 1,6-bisphosphate (F1,6BP) to pyruvate generates exactly 2 NADH and a net 2 ATP per molecule of F1,6BP, as this payoff phase skips the initial ATP investments.

      Glycolysis Stages Overview

      Fructose 1,6-bisphosphate splits into dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P) by aldolase. DHAP converts to G3P, yielding two G3P molecules that proceed through oxidation, phosphorylation, and dephosphorylation to form two pyruvates.

      • G3P dehydrogenase oxidizes each G3P to 1,3-bisphosphoglycerate, producing 1 NADH per G3P (total 2 NADH).

      • Phosphoglycerate kinase generates 1 ATP per 1,3-BPG via substrate-level phosphorylation (total 2 ATP).

      • Pyruvate kinase produces another 1 ATP per phosphoenolpyruvate (total 2 more ATP, or 4 gross ATP).

      No ATP is consumed after F1,6BP formation, so net yield matches gross: 2 NADH and 2 ATP (not 4, as full glucose glycolysis nets 2 ATP after subtracting 2 early investments).

      Option Analysis

      Option	NADH	ATP	Explanation
      A	2 moles	4 moles	Incorrect—gross ATP is 4, but question specifies “formation” as net from this segment (2 ATP); full glycolysis confuses this.
      B	1 mole	1 mole	Incorrect—underestimates both; each G3P arm yields 1 NADH and 2 ATP (doubled).​
      C	2 moles	2 moles	Correct—precisely matches payoff phase products: 2 NADH from oxidation, net 2 ATP (4 produced, 0 invested here).
      D	2.5 moles	2 moles	Incorrect—NADH is whole number (2); no half-mole in standard eukaryotic glycolysis.​

      In glycolysis, the conversion of fructose 1,6-bisphosphate to pyruvate marks the energy payoff phase, crucial for ATP and NADH production in cellular respiration. This step, post the energy investment phase, directly yields 2 moles of NADH and 2 moles of ATP from one F1,6BP molecule, powering anaerobic and aerobic metabolism.

      Payoff Phase Steps

      Aldolase cleaves F1,6BP into DHAP and G3P; DHAP isomerizes to G3P. Each G3P then:

      • Forms 1,3-bisphosphoglycerate + NADH (glyceraldehyde-3-phosphate dehydrogenase).

      • Yields ATP + 3-phosphoglycerate (phosphoglycerate kinase).

      • Converts to pyruvate + ATP (pyruvate kinase).

      Total: 2 NADH, 4 ATP gross (net 2, as no investment here).

      Exam Relevance

      For competitive exams, note: full glucose glycolysis nets 2 ATP/2 NADH after 2 ATP cost; from F1,6BP, it’s 4 ATP gross/2 NADH. Options like “4 ATP” trap those mixing phases. Ideal for GATE Life Sciences prep on metabolic yields.