Anaerobic Respiration : Study Notes

For the complete syllabus, check out our PMDC MDCAT Syllabus 2025 article.

Respiration

• Respiration is the process of oxidizing food material in living organisms to release energy.

Types of Respiration

1. Anaerobic Respiration
   • Occurs without atmospheric oxygen, resulting in the incomplete oxidation of carbohydrates.
   • End products: Alcohols and organic acids with minimal energy release. This process is also known as fermentation.
2. Aerobic Respiration
   • Takes place in the presence of oxygen, leading to complete oxidation of carbohydrates.
   • End products: CO₂ and H₂O, with a higher energy release.

Alcoholic Fermentation

• Step I: Pyruvic acid undergoes decarboxylation to produce acetaldehyde (CH₃CHO), releasing CO₂.
  • Equation: CH₃COCOOH → CH₃CHO + CO₂
• Step II: Acetaldehyde is reduced by NADH + H⁺ to form ethyl alcohol (CH₃CH₂OH).
  • Equation: CH₃CHO + NADH + H⁺ → CH₃CH₂OH + NAD⁺

Lactic Acid Fermentation

• NADH + H⁺ transfers its hydrogen to pyruvic acid, forming lactic acid.
  • Equation: CH₃COCOOH + NADH + H⁺ → CH₃CHOHCOOH

Additional Notes

• During intense exercise, muscle cells in animals and humans undergo anaerobic respiration due to limited oxygen supply, converting pyruvic acid into lactic acid.

Explore our MDCAT webapp for tests, video lectures, and complete prep resources.