Total ATP equivalents required for gluconeogenesis (per glucose) Counting high-energy phosphate equivalents, how many ATP equivalents are consumed to produce 1 mole of glucose by gluconeogenesis from pyruvate/lactate?

Introduction / Context:
Energetic bookkeeping in metabolism often expresses energy costs as “ATP equivalents.” In gluconeogenesis, both ATP and GTP are consumed; GTP is energetically equivalent to ATP because it donates a terminal phosphate in analogous reactions. This question asks you to sum those costs per glucose synthesized.

Given Data / Assumptions:

• Pathway from 2 pyruvate → 1 glucose.
• Direct nucleotide costs: 4 ATP + 2 GTP per glucose.
• NADH requirements are excluded from ATP-equivalent counting here.

Concept / Approach:

Convert GTP usage into ATP equivalents (1 GTP ≈ 1 ATP equivalent). Then add ATP + GTP counts to obtain total high-energy phosphate consumption.

Step-by-Step Solution:

Verification / Alternative check:

Standard texts and problem sets list 6 high-energy phosphate bonds per glucose for the canonical route from pyruvate, in agreement with detailed stoichiometry.

Why Other Options Are Wrong:

Options 2 and 4 underestimate; 8 and 10 overstate the requirement. The accepted energy cost is 6 ATP equivalents.

Common Pitfalls:

Forgetting to count both 3-phosphoglycerate kinase reactions (twice) or miscounting GTP separately from ATP equivalents.

Final Answer:

6