Question

Answer the following question.

How are glycolysis, TCA cycle, and electron transport chain-linked? Explain.

Answer 1

Glycolysis, TCA cycle and electron transport chain are linked in the following manner:

1. The coenzymes are initially present in the form of NAD⁺ and FAD⁺ which latter get reduced to NADH+H⁺ and FADH+H⁺ by accepting the hydrogen from the organic substrate during glycolysis, link reaction, and Krebs cycle.
2. During glycolysis, glucose is oxidized to two molecules of pyruvic acid with a net gain of 2 molecules of NADH+H⁺.
3. This pyruvic acid undergoes a link reaction to form two molecules of acetyl CoA and two molecules of NADH+H⁺.
4. Acetyl CoA, thus formed enters into the Krebs cycle and it gets completely oxidized to CO₂ and H₂O; with a net gain of 6 NADH+H⁺ and 2 FADH+H⁺ are formed.
5. During ETS, reduced coenzymes are reoxidized to NAD⁺ and FAD⁺ with a net gain of 34 ATPs.
6. The ATPs thus formed are used during glycolysis.
7. The oxidized NAD⁺ and FAD⁺ will again accept the hydrogen from the organic substrate. Thus, reduced coenzymes are converted back to their oxidized forms by dehydrogenation to keep the process going.