Question

Compare the oxidation states of glucose and pyruvate. Explain why glycolysis generates NADH

Short answer

In Glycolysis process, NADH is formed from NAD⁺.

Step-by-step solution

Glycolysis

Glycolysis is the initial phase in cellular respiration, and it happens to glucose. Glycolysis is an anaerobic (oxygen-free) process. It occurs within the cytoplasm. Pyruvate is the ultimate result of glycolysis, and its destiny is determined by the availability of oxygen.

Oxidation state of Glucose

It's a cytoplasmic protein.

Is the partial oxidation of glucose (6 carbons) into 2 carbons of pyruvate (pyruvic acid).

Two hydrogen carriers (2 x NADH⁺H⁺) were reduced in the process of oxidation.

A total of two ATP molecules were synthesised (four molecules were made, but only two were utilised).

Oxidation state of Pyruvate

Pyruvate is delivered to the mitochondria for full oxidation (further breakdown).

Large amounts of reduced hydrogen carriers (NADH⁺H⁺and FADH₂) result from this extra oxidation.

In the presence of oxygen, the decreased hydrogen carriers will release their stored energy to make additional ATP. So, compared to pyruvate, glycolysis has a lower oxidation state

Conclusion

NADH is created from NAD⁺during glycolysis. The cell's redox balance must be maintained in order for further glycolysis activities to occur. In the presence of oxygen, ETC generates NAD⁺. Pyruvate is transformed to acetyl CoA, which enters the TCA cycle and is oxidised to CO₂.