Which of the following is carrying both electrons in the energized state and protons for transfer to a substrate? Group of answer choices
A. ATP
B. NAD+
C. NADPH
D. A and B
E. B and C
The correct answer and explanation is:
The correct answer is C. NADPH.
Explanation:
NADPH (Nicotinamide adenine dinucleotide phosphate) is a coenzyme that plays a critical role in biochemical reactions, particularly in anabolic pathways like the Calvin cycle in photosynthesis. NADPH functions as a carrier of both electrons and protons (hydrogen ions) in their energized state.
- NADPH carries electrons in the form of a hydride ion (H−), which consists of two electrons and one proton. This allows NADPH to participate in various reduction reactions where it donates these high-energy electrons to substrates, aiding in the synthesis of molecules like glucose and fatty acids.
- ATP (Adenosine Triphosphate), while essential for energy transfer, does not carry both electrons and protons. ATP is primarily involved in transferring energy through the phosphate groups, facilitating processes like phosphorylation, but it does not directly carry electrons or protons for substrate reduction.
- NAD+ (Nicotinamide adenine dinucleotide) is the oxidized form of NADPH and is involved in electron transfer in oxidation reactions. NAD+ accepts electrons and protons during metabolic processes like glycolysis and the citric acid cycle. However, it is not in its energized state (NAD+ is not carrying electrons or protons in an energized form).
Thus, NADPH is the correct choice because it is the molecule that carries both electrons in the energized state and protons for transfer to substrates during biochemical reactions.