What is the role of NADH in cellular respiration?

• A. It acts as a substrate for glycolysis
• B. It transfers electrons to the electron transport chain
• C. It serves as a source of carbon for cellular metabolism
• D. It inhibits glycolysis

Answer: (B)

NADH plays a crucial role in cellular respiration, particularly in the process of oxidative phosphorylation, where it functions as an electron carrier. After being generated during glycolysis and the citric acid cycle, NADH transfers electrons to the electron transport chain (ETC) located in the mitochondrial inner membrane. This transfer of electrons is essential for the production of ATP, as it drives the proton gradient that powers ATP synthase.

Through this mechanism, NADH helps facilitate the conversion of biochemical energy from nutrients into a more usable form, namely ATP, which is vital for cellular functions. By donating electrons to the ETC, NADH contributes to the overall energy yield of cellular respiration. This highlights its role as a pivotal molecule in energy metabolism rather than serving any of the other functions described in the incorrect options.