Aerobic respiration yield: During complete aerobic respiration of glucose, most ATP yield in prokaryotes and eukaryotes is captured by which process?

Introduction / Context:
Glucose oxidation to CO2 and H2O is a multi-stage process involving glycolysis, pyruvate oxidation, the TCA cycle, and oxidative phosphorylation. Understanding where the bulk of ATP arises is central to microbial energetics and physiology.

Given Data / Assumptions:

• Glycolysis and TCA cycle produce limited ATP directly by substrate-level phosphorylation.
• NADH and FADH2 carry high-energy electrons to the electron transport chain (ETC).
• Proton motive force drives ATP synthase to generate most ATP.

Concept / Approach:

Substrate-level phosphorylation contributes a small fraction (e.g., 2 ATP from glycolysis and 1 GTP/ATP per TCA turn). The majority of ATP comes from oxidative phosphorylation as electrons from NADH (and FADH2) flow through respiratory complexes to the terminal electron acceptor (oxygen in aerobes), pumping protons and powering ATP synthase.

Step-by-Step Solution:

Verification / Alternative check:

Quantitative yields (organism-dependent) consistently show oxidative phosphorylation surpassing substrate-level phosphorylation in ATP contribution under aerobic conditions.

Why Other Options Are Wrong:

Substrate-level phosphorylation: necessary but minor contributor.

Long-chain fatty acid oxidation: relevant to lipid catabolism, not specifically glucose respiration.

Formic-hydrogen lyase: associated with certain anaerobic fermentations, not aerobic glucose respiration.

Common Pitfalls:

Overestimating substrate-level ATP; forgetting the tight coupling between electron transport, proton motive force, and ATP synthesis.

Final Answer:

electron transport of electrons from NADH