Location and fate of glycolysis products Glycolysis occurs in which cellular location, produces what immediate product, and in the presence of oxygen that product enters which organelle to complete cellular respiration?

Introduction / Context:
Glycolysis is the central pathway that converts glucose to pyruvate. Understanding where it occurs and what happens to pyruvate under aerobic conditions is foundational for biochemistry, physiology, and medicine.

Given Data / Assumptions:

• Glycolysis takes place in the cytosol of both prokaryotic and eukaryotic cells.
• End product is pyruvate (plus ATP and NADH).
• With oxygen present, pyruvate is oxidatively decarboxylated to acetyl CoA and enters the TCA cycle in mitochondria.

Concept / Approach:

The correct chain is: cytosolic glycolysis → pyruvate → mitochondrial matrix (pyruvate dehydrogenase) → acetyl CoA → citric acid cycle → oxidative phosphorylation. Fermentation occurs when oxygen is scarce and remains cytosolic, producing lactate or ethanol, not completing respiration in mitochondria.

Step-by-Step Solution:

Verification / Alternative check:

Biochemical fractionation studies localize pyruvate dehydrogenase to mitochondria in eukaryotes, confirming the entry of pyruvate for aerobic respiration.

Why Other Options Are Wrong:

Glucose is the substrate, not the product. Fermentation does not occur in mitochondria. Chloroplasts are not involved in respiration. DNA replication occurs in the nucleus and is unrelated to glycolysis routing.

Common Pitfalls:

Assuming pyruvate is converted to acetyl CoA in the cytosol in eukaryotes; that is a mitochondrial process.

Final Answer:

Cytosol; pyruvate; mitochondrion to complete cellular respiration