Citric acid cycle connections — What do coenzyme A, carbon dioxide (CO2), oxaloacetate (OAA), and FADH2 have in common in core metabolism?

Introduction / Context:
The citric acid cycle is a central metabolic hub. CoA forms acetyl-CoA to enter the cycle, CO2 is released during decarboxylation steps, oxaloacetate is both the starting and ending four-carbon acceptor, and FADH2 is a reduced cofactor produced at succinate dehydrogenase (Complex II).

Given Data / Assumptions:

• Acetyl-CoA condenses with OAA to form citrate.
• CO2 is produced at isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase steps.
• FAD is reduced to FADH2 when succinate is oxidized to fumarate.

Concept / Approach:
Relate each item to a specific TCA step to confirm their commonality with the Krebs cycle.

Step-by-Step Solution:

Verification / Alternative check:
Standard biochemical maps show these roles explicitly in the TCA cycle scheme.

Why Other Options Are Wrong:

Common Pitfalls:
Separating TCA from oxidative phosphorylation; they are linked via NADH/FADH2 supply.

Final Answer:
They are all components or products of the citric acid cycle.