Which one of the following is formed as pyruvate is converted to acetyl CoA during pyruvate oxidation?

• A. NADH
• B. ATP
• C. Lactic acid
• D. FADH2

Answer: (A)

Verified step by step guidance

1. Understand the process of pyruvate oxidation, which occurs in the mitochondria after glycolysis. Pyruvate, a three-carbon molecule, is converted into acetyl CoA, a two-carbon molecule, in preparation for the citric acid cycle.
2. Recognize that during the conversion of pyruvate to acetyl CoA, a molecule of carbon dioxide (CO2) is released as a byproduct. This is a decarboxylation reaction.
3. Identify that during this conversion, electrons are transferred to NAD+ (nicotinamide adenine dinucleotide), reducing it to NADH. This is an important step as NADH will carry electrons to the electron transport chain.
4. Note that ATP is not directly produced during the conversion of pyruvate to acetyl CoA. Instead, the energy captured in NADH will be used later in the electron transport chain to produce ATP.
5. Understand that lactic acid and FADH2 are not products of pyruvate oxidation. Lactic acid is produced during anaerobic respiration, and FADH2 is produced later in the citric acid cycle, not during the conversion of pyruvate to acetyl CoA.