Which of the following is not true of the reaction catalyzed by the pyruvate dehydrogenase complex?

• A. It releases carbon dioxide as a waste product.
• B. It produces NADH as a byproduct.
• C. It converts pyruvate into acetyl-CoA.
• D. It occurs in the cytoplasm of the cell.

Answer: (D)

Verified step by step guidance

1. Understand the role of the pyruvate dehydrogenase complex: It is an enzyme complex that catalyzes the conversion of pyruvate into acetyl-CoA, a crucial step linking glycolysis to the citric acid cycle.
2. Identify the location of the reaction: The pyruvate dehydrogenase complex operates in the mitochondria, not in the cytoplasm. This is a key point to remember as it differentiates this process from glycolysis, which occurs in the cytoplasm.
3. Recognize the byproducts of the reaction: The conversion of pyruvate to acetyl-CoA by the pyruvate dehydrogenase complex results in the release of carbon dioxide (CO2) and the production of NADH, which are both true statements about the reaction.
4. Evaluate the given statements: Compare each statement with the known facts about the pyruvate dehydrogenase complex. The statement that it occurs in the cytoplasm is incorrect, as the reaction takes place in the mitochondria.
5. Conclude which statement is not true: Based on the analysis, the statement 'It occurs in the cytoplasm of the cell' is not true, as the reaction actually occurs in the mitochondria.