Which ingredients are needed to transform NADP+ to NADPH? an electron and two hydrogen ions two electrons and two hydrogen ions two electrons and a hydrogen ion an electron and a hydrogen ion
The correct answer and explanation is:
The correct answer is: two electrons and a hydrogen ion
Explanation:
NADP⁺ (nicotinamide adenine dinucleotide phosphate) is a coenzyme involved in many biochemical reactions, especially in photosynthesis and anabolic pathways. It functions as an electron carrier, cycling between its oxidized form (NADP⁺) and its reduced form (NADPH).
To convert NADP⁺ into NADPH, a reduction reaction must occur. Reduction means gaining electrons (and typically associated protons, H⁺). Specifically, NADP⁺ gains:
- Two electrons (2 e⁻)
- One hydrogen ion (1 H⁺)
This process adds a hydride ion (H⁻), which consists of one proton and two electrons, to NADP⁺. The overall chemical equation looks like this:
$$
\text{NADP}^+ + 2e^- + H^+ \rightarrow \text{NADPH}
$$
Why two electrons and one hydrogen ion?
- NADP⁺ is reduced by accepting a hydride ion (H⁻), which contains two electrons and one proton.
- Additionally, there is usually one more proton (H⁺) released into the surrounding solution to balance the charge, but the molecule itself accepts one H⁺ along with the two electrons.
- The hydride addition reduces the nicotinamide ring within NADP⁺, turning it into NADPH.
Why not other options?
- An electron and two hydrogen ions would not balance the charge and structure properly.
- Two electrons and two hydrogen ions would add too many protons; NADPH only incorporates one hydrogen atom (one proton plus two electrons).
- An electron and a hydrogen ion is insufficient because the addition of one electron alone cannot reduce NADP⁺; two electrons are required for the full reduction.
Biological relevance:
In photosynthesis, NADP⁺ accepts electrons generated during the light reactions to form NADPH, which then serves as a reducing agent in the Calvin cycle to help synthesize glucose from carbon dioxide. NADPH carries high-energy electrons and is essential for anabolic reactions in cells, including lipid and nucleic acid synthesis.