Question

11 multiple choice 10 points which of the following best describes the function of the coenzymes nad+ and fad in eukaryotic cellular respiration? they accept electrons during oxidation - reduction reactions. they serve as final electron acceptors in the electron transport chain. they participate in hydrolysis reactions by accepting protons from water molecules. they participate directly in the phosphorylation of adp to atp. they aid vitamins such as niacin in the breakdown of glucose.

Explanation:

• For the first option: In cellular respiration, during oxidation - reduction reactions (such as in glycolysis, the citric acid cycle), \(NAD^{+}\) is reduced to \(NADH\) (\(NAD^{+}+2H^{+}+2e^{-}\to NADH + H^{+}\)) and \(FAD\) is reduced to \(FADH_{2}\) (\(FAD + 2H^{+}+2e^{-}\to FADH_{2}\)). They act as electron acceptors.
• For the second option: The final electron acceptor in the electron - transport chain in eukaryotic cellular respiration is \(O_{2}\) (not \(NAD^{+}\) or \(FAD\)).
• For the third option: \(NAD^{+}\) and \(FAD\) are involved in redox reactions (not hydrolysis reactions which involve the breaking of bonds with the addition of water).
• For the fourth option: They are not directly involved in the phosphorylation of \(ADP\) to \(ATP\). The phosphorylation of \(ADP\) to \(ATP\) in oxidative phosphorylation is mainly related to the proton - motive force generated by the electron - transport chain.
• For the fifth option: Vitamins like niacin are precursors for \(NAD^{+}\) (niacin is used to synthesize \(NAD^{+}\)), but \(NAD^{+}\) and \(FAD\) do not aid vitamins in the breakdown of glucose in the way described. It's the other way around (vitamins are used to make the co - enzymes).

Answer:

They accept electrons during oxidation - reduction reactions.