What is the Difference Between NADH and FADH2?

The main difference between NADH and FADH2 lies in the number of ATP molecules they produce during oxidative phosphorylation and the specific complexes they donate electrons to in the electron transport system (ETS).

• NADH: This is the reduced form of the coenzyme NAD, which is made up of two nucleotides: adenine and nicotinamide. NADH is derived from vitamin B3 or niacin. During oxidative phosphorylation, each NADH molecule generates three ATP molecules. In the ETS, NADH transfers electrons to complex I.
• FADH2: This is the reduced form of the coenzyme FAD, which is made up primarily of riboflavin. FADH2 is derived from vitamin B2 or riboflavin. During oxidative phosphorylation, each FADH2 molecule produces two ATP molecules. In the ETS, FADH2 transports electrons to complex II.

Both NADH and FADH2 are involved in oxidation-reduction reactions and help in the transfer of electrons. They can be synthesized in the body and participate in various metabolic pathways, including carbohydrate, fatty acid, amino acid, and nucleotide metabolism.

Comparative Table: NADH vs FADH2

Here is a table highlighting the differences between NADH and FADH2:

Both NADH and FADH2 are coenzymes that play essential roles in cellular energy production. They serve as electron carriers in various reactions and are involved in different steps of cellular respiration.