AP BIOLOGY

Detailed explanation-1: -NAD+ has more chemical energy than NADH. NAD+ donates high energy electrons to the electron transport chain.

Detailed explanation-2: -NAD+ can be reduced to NADH via dehydrogenases and can also be phosphorylated to NADP+ via NAD+ kinases (NADKs). The NAD+/NADH redox couple is known as a regulator of cellular energy metabolism, that is, of glycolysis and mitochondrial oxidative phosphorylation.

Detailed explanation-3: -It plays a key role in energy metabolism by accepting and donating electrons. The low energy form NAD+ shown at left is raised to the high energy form NADH. The change in the form of the active nicotinamide group in NADH is indicated above. It accepts two electrons and a hydrogen in reaching the high energy state.

Detailed explanation-4: -When NAD+ is converted to NADH, it gains two things: First, a charged hydrogen molecule (H+) and next, two electrons. As electrons are negatively charged, the combination of the positively charged NAD+ and H+, coupled with two electrons, effectively cancel each other out and neutralize the resulting NADH molecule.