During conversion of one molecule of glucose to two molecules of lactate under anaerobic conditions, what is the net ATP yield, and at which reactions does substrate-level phosphorylation occur?

• A Net 2 ATP, at phosphoglycerate kinase and pyruvate kinase ✓
• B Net 4 ATP, at hexokinase and phosphofructokinase-1
• C Net 2 ATP, at glyceraldehyde-3-phosphate dehydrogenase and enolase
• D Net 6 ATP, at phosphoglycerate kinase and enolase

Explanation

Anaerobic glycolysis yields a gross of 4 ATP per glucose from two substrate-level phosphorylation steps per half-glucose: phosphoglycerate kinase (1,3-BPG to 3-PG) and pyruvate kinase (PEP to pyruvate). Two ATP are invested at hexokinase and PFK-1, giving a net of 2. Glyceraldehyde-3-phosphate dehydrogenase and enolase produce NADH and water respectively, not ATP directly.

Reference: Lippincott Illustrated Reviews: Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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