Question

4. Explain what happens to glucose during glycolysis and respiration in terms of oxidation and reduction.

Answer 1

During glycolysis, a glucose molecule (6 carbon) is oxidized and cleaved into two molecules of pyruvate (3 carbon). In the 4^th step of glycolysis catalysed by aldolase, furstose-1,6-bisphosphate is cleaved into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate both of which are later converted into two molecules of pyruvate while producing 2 NADH and 4 ATPs.

Pyruvate is further oxidized by pyruvate dehydrogenase into CO2 and acetyl-CoA (2 carbon) which is oxidized into CO2 completely via TCA cycle while generating 3 NADH, 1 FADH2, and 1 GTP.

In this way, a glucose molecule is completely oxidized into 6 CO₂, 10 NADH, 2 FADH2, 4 ATPs, and 2 GTP by glycolysis, pyruvate dehydrogenase, and TCA cycle.

These reducing equivalents (NADH and FADH2) generate ATP via electron transport chain and oxidative phosphorylation.