Despite Their Overall Similarity, NADH and NADPH Are Not Used

Multiple Choice

Despite their overall similarity, NADH and NADPH are not used indiscriminately by the cell. What are the distinctive features of these two carrier molecules?

A) NADPH has an extra phosphate near its nicotinamide ring, giving it distinct electron-transfer properties.
B) In the cell, NADH is usually in excess over NAD⁺, but NADP⁺ is usually in excess over NADPH.
C) NADH is normally involved in anabolic reactions, whereas NADPH is normally involved in catabolism.
D) Both NADPH and NADH are recognized by the same enzymes with similar affinities, since the extra phosphate group in NADPH is not involved in such recognition.
E) In the cell, NADH is found mostly in the form that acts as an oxidizing agent, whereas NADPH is found mostly in the form that acts as a reducing agent.