In cellular respiration, which process directly connects glycolysis to the citric acid cycle by converting pyruvate into acetyl-CoA?

• A. Fermentation of pyruvate to lactate to regenerate $NA{D}^{+}$
• B. Pyruvate oxidation by the pyruvate dehydrogenase complex (oxidative decarboxylation of pyruvate to acetyl-CoA)
• C. Oxidation of acetyl-CoA to $C_{O}2$ during the citric acid cycle
• D. Conversion of glucose to pyruvate via glycolysis

Answer: (B)

Verified step by step guidance

1. Identify the key molecules involved: glycolysis produces pyruvate, and the citric acid cycle uses acetyl-CoA as a substrate.
2. Understand that the process connecting glycolysis to the citric acid cycle must convert pyruvate into acetyl-CoA.
3. Recognize that this conversion is catalyzed by the pyruvate dehydrogenase complex through oxidative decarboxylation.
4. Write the overall reaction for pyruvate oxidation: \(\text{Pyruvate} + \text{CoA} + \text{NAD}^+ \rightarrow \text{Acetyl-CoA} + \text{CO}_2 + \text{NADH}\).
5. Note that this step links the two pathways by producing acetyl-CoA, which then enters the citric acid cycle for further oxidation.