In anabolic reactions that involve the synthesis of a large molecule from smaller precursor molecules, NADH and ATP are consumed when they provide the needed electrons or energy.
In catabolic reactions that involve the breakdown of a molecule into smaller subunits, such as glucose to pyruvate, NADH and ATP are produced.
In the reaction Pyruvate +NADH-Lactate +NAD, pyruvate is being reduced.
In the reaction Pyruvate NADH-Lactate +NAD, NADH is being oxidized.
Explanation:
Being involved in synthesis, anabolic reactions require energy in the form of energy storing molecules such as NADH and ATP. Anabolic processes utilize energy produced by the catabolism of complex compounds.
Catabolic processes produce energy or energy storing compounds by breaking down complex substances into simpler ones. All steps of cellular respiration are catabolic processes since they generate energy in the form of ATP or energy yielding molecules such as NADH and FADH2.
Anaerobic respiration takes place during intense physical activity due to which adequate oxygen does not reach the cells. Insufficient oxygen shuttles the pyruvate molecules produced by glycolysis into the lactic acid pathway that reduces pyruvate into lactic acid.
Since, NADH is donating its H+, it is being oxidized to NAD+.
