In mature erythrocytes, the end-product of glycolysis that contains the carbons of glucose is:

Correct option is C

Explanation:

• Mature erythrocytes (red blood cells) lack mitochondria, which means they cannot undergo aerobic respiration (TCA cycle and oxidative phosphorylation).
• Instead, they rely entirely on anaerobic glycolysis for ATP production.
• The final product of glycolysis in anaerobic conditions (as seen in erythrocytes) is lactate.
• In glycolysis, one glucose molecule (C₆H₁₂O₆) is broken down into two molecules of pyruvate (C₃H₄O₃).
• Since erythrocytes lack mitochondria, pyruvate is converted into lactate (C₃H₆O₃) by lactate dehydrogenase (LDH) in order to regenerate NAD⁺.
• This conversion allows glycolysis to continue producing ATP through substrate-level phosphorylation.

Thus, in mature erythrocytes, the end-product of glycolysis that contains the carbons of glucose is lactate (option c).

Information Booster

1. Glycolysis occurs in the cytoplasm and is the primary source of ATP in erythrocytes.
2. Erythrocytes lack mitochondria, preventing them from using the TCA cycle or oxidative phosphorylation.
3. Pyruvate is reduced to lactate via lactate dehydrogenase (LDH) to regenerate NAD⁺, which is essential for glycolysis.
4. Lactate accumulation can lead to lactic acidosis under anaerobic conditions or excessive glycolysis.
5. The Cori cycle helps transport lactate to the liver, where it is converted back to glucose via gluconeogenesis.
6. Other anaerobic organisms (e.g., yeast) produce ethanol instead of lactate, but humans use lactate fermentation.

Additional Information

• Option (a) Ethanol: Ethanol is not produced in human cells; it is a fermentation product of yeast.
• Option (b) Pyruvate: Pyruvate is the intermediate of glycolysis but is not the final product in erythrocytes.
• Option (d) Acetaldehyde: Acetaldehyde is an intermediate in ethanol fermentation, which does not occur in human cells.