Multiple Choice
During the catabolism of glucose, which chemical compound enters the mitochondria to undergo pyruvate oxidation?
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Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism
Pyruvate Oxidation
Multiple Choice
Which of the following coenzymes are required for the oxidation of pyruvate to acetyl-CoA by the pyruvate dehydrogenase complex?
A
FADH\(_2\), ATP, Ubiquinone, Vitamin B\(_{12}\)
B
NAD\(^+\), Biotin, Coenzyme Q, Tetrahydrofolate
C
NADP\(^+\), Biotin, Coenzyme Q, Pyridoxal phosphate (PLP)
D
NAD\(^+\), Coenzyme A, Thiamine pyrophosphate (TPP), Lipoic acid, FAD
Verified step by step guidance1
Step 1: Understand the role of the pyruvate dehydrogenase complex (PDC). It is a multi-enzyme complex responsible for converting pyruvate into acetyl-CoA, a key intermediate in cellular respiration. This process involves oxidative decarboxylation and requires several coenzymes.
Step 2: Identify the coenzymes involved in the reaction. The pyruvate dehydrogenase complex uses five essential coenzymes: NAD\(^+\) (nicotinamide adenine dinucleotide), Coenzyme A (CoA), Thiamine pyrophosphate (TPP), Lipoic acid, and FAD (flavin adenine dinucleotide). Each plays a specific role in the reaction mechanism.
Step 3: Exclude the incorrect options. For example, FADH\(_2\) is the reduced form of FAD and is not directly required in this reaction. ATP, Ubiquinone, Vitamin B\(_{12}\), Biotin, Coenzyme Q, Tetrahydrofolate, NADP\(^+\), and Pyridoxal phosphate (PLP) are not involved in the pyruvate dehydrogenase complex reaction.
Step 4: Match the correct coenzymes to their functions: (a) TPP is involved in the decarboxylation of pyruvate, (b) Lipoic acid acts as a carrier for acyl groups, (c) Coenzyme A accepts the acetyl group to form acetyl-CoA, (d) FAD and NAD\(^+\) are involved in electron transfer during the oxidation process.
Step 5: Summarize the correct answer. The coenzymes required for the oxidation of pyruvate to acetyl-CoA by the pyruvate dehydrogenase complex are NAD\(^+\), Coenzyme A, Thiamine pyrophosphate (TPP), Lipoic acid, and FAD.
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