Which molecule acts as an electron carrier that becomes NADPH by gaining two electrons?

Which molecule acts as an electron carrier that becomes NADPH by gaining two electrons?

• A. NADP+
• B. NAD+
• C. FAD
• D. ATP

Answer: (A)

The main concept is how a coenzyme accepts electrons to become a reduced carrier that drives biosynthetic work. NADP+ accepts two electrons (and a proton) to form NADPH, serving as the electron carrier in photosynthetic pathways. This NADPH carries reducing power to drive reactions like carbon fixation and other biosynthetic processes. The NADP+ molecule is the oxidized form, and it becomes NADPH when reduced. NAD+ would be reduced to NADH in many cellular respiration steps, not to NADPH. FAD is reduced to FADH2, not to NADPH. ATP isn’t a redox carrier at all; it stores energy, not electrons.

The main concept is how a coenzyme accepts electrons to become a reduced carrier that drives biosynthetic work. NADP+ accepts two electrons (and a proton) to form NADPH, serving as the electron carrier in photosynthetic pathways. This NADPH carries reducing power to drive reactions like carbon fixation and other biosynthetic processes. The NADP+ molecule is the oxidized form, and it becomes NADPH when reduced.

NAD+ would be reduced to NADH in many cellular respiration steps, not to NADPH. FAD is reduced to FADH2, not to NADPH. ATP isn’t a redox carrier at all; it stores energy, not electrons.