Total ATP yield in eukaryotic cells (yeast/fungi) A yeast or fungal cell completely oxidizing one molecule of glucose typically nets how many ATP molecules under classical textbook accounting?

Introduction / Context:
Textbook ATP accounting often assigns standard integer values to ATP yields. For eukaryotes, the classic number for complete oxidation of one glucose is 36 ATP, reflecting mitochondrial respiration and transport costs. Recognizing this convention helps reconcile related questions on P/O ratios and pathway contributions.

Given Data / Assumptions:

• Classic yields: 3 ATP per NADH, 2 ATP per FADH₂.
• Two ATP are consumed or not realized due to cytosolic NADH shuttling into mitochondria.
• Prokaryotes are often cited as yielding 38 ATP per glucose under similar assumptions.

Concept / Approach:
Glycolysis (net 2 ATP + 2 NADH), pyruvate oxidation (2 NADH), TCA cycle (2 ATP/GTP + 6 NADH + 2 FADH₂). Applying classic P/O ratios and accounting for shuttle costs yields 36 ATP in eukaryotes. Modern estimates are lower (about 30–32), but many exams use the traditional figure, especially when paired with a “3 ATP per NADH” assumption elsewhere.

Step-by-Step Solution:
Sum ATP from substrate-level phosphorylation: 2 (glycolysis) + 2 (TCA) = 4.Sum ATP from NADH/FADH₂ using classic ratios and subtract shuttle costs to reach ~36.Select “36” as the standard textbook answer.

Verification / Alternative check:
Prokaryotic totals are traditionally given as 38 ATP, reinforcing that the eukaryotic figure is 36 under the classic framework.

Why Other Options Are Wrong:

• 38: classic prokaryotic figure, not eukaryotic with shuttling cost.
• 34/32/30: align with various modern estimates but not with the conventional exam total tied to a 3/2 P/O scheme.

Common Pitfalls:
Switching between modern mechanistic yields and legacy numbers within the same problem set; stay consistent with the question set’s conventions.

Final Answer:
36.