Question

question 3
which of the following correctly identifies an oxidation or reduction event in the krebs cycle?
fad is reduced to fadh₂
atp is oxidized to adp
pyruvate is reduced to acetyl-coa
glucose is oxidized to citrate
nad+ is oxidized to nadh

Explanation:

• In the Krebs cycle, \(FAD\) (flavin adenine dinucleotide) is reduced to \(FADH_2\).
• \(NAD^+\) is reduced (not oxidized) to \(NADH\) in the Krebs cycle.
• Glucose is not directly oxidized to citrate in the Krebs cycle; pyruvate is first converted to acetyl - CoA, and then acetyl - CoA enters the Krebs cycle.
• Pyruvate is oxidized (not reduced) to acetyl - CoA (this is actually the transition step before the Krebs cycle, but in terms of redox, it is an oxidation process).
• \(ATP\) is synthesized (not oxidized to \(ADP\)) in the Krebs cycle (through substrate - level phosphorylation).

Answer:

FAD is reduced to \(FADH_2\)