Ans.
Glucose is a 6-carbon molecule, while pyruvate is a 3-carbon molecule. In all organisms, glucose is first converted into pyruvate in the cytoplasm.
Further breakdown of pyruvate can happen in any of the following ways:
- In Yeast: Breakdown of pyruvate takes place in absence of oxygen. Pyruvate is broken down into ethanol and carbon dioxide. It is called anaerobic respiration.
- In mitochondria: Breakdown of pyruvate takes place in presence of oxygen. Pyruvate is broken down into carbon dioxide and water. It is called aerobic respiration. It is found in most of the living beings.
- In muscle cells: The energy demand from muscle cells suddenly increases during strenuous physical activities. This is compensated by anaerobic respiration in muscle cells. In this, pyruvate is broken down into lactic acid.
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