Fates of Pyruvate under Anaerobic Conditions Fermentation

Pyruvate occupies an important junction in carbohydrate catabolism (Fig. 14-3). Under aerobic conditions pyruvate is oxidized to acetate, which enters the citric acid cycle and is oxidized to CO2 and H2O, and NADH formed by the dehydrogenation of glyceraldehyde 3-phosphate is ultimately reoxidized to NAD+ by passage of its electrons to O2 in mitochondrial respiration. However, under hypoxic conditions, as in very active skeletal muscle, in submerged plant tissues, or in lactic acid bacteria, NADH generated by glycolysis cannot be re-oxidized by O2. Failure to regenerate NAD+ would leave the cell with no electron acceptor for the oxidation of glyceraldehyde 3-phosphate, and the energy-yielding reactions of glycolysis would stop. NAD+ must therefore be regenerated in some other way.

The earliest cells lived in an atmosphere almost devoid of oxygen and had to develop strategies for deriving energy from fuel molecules under anaerobic conditions. Most modern organisms have retained the ability to constantly regenerate NAD+ during anaerobic glycolysis by transferring electrons from NADH to form a reduced end product such as lactate or ethanol.

Pyruvate Is the Terminal Electron Acceptor in Lactic Acid Fermentation

When animal tissues cannot be supplied with sufficient oxygen to support aerobic oxidation of the pyruvate and NADH produced in glycolysis, NAD+ is regenerated from NADH by the reduction of pyruvate to lactate. As mentioned earlier, some tissues and cell types (such as erythrocytes, which have no mitochondria and thus cannot oxidize pyruvate to CO2) produce lactate from glucose even under aerobic conditions. The reduction of pyruvate is catalyzed by lactate dehydrogenase, which forms the l isomer of lactate at pH 7:

Glucose

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • tom schmitt
    What are the fates of pyruvate under hypoxic/anaerobic conditions?
    2 years ago
  • kaiju saijonmaa
    What is the fate of pyruvate in anaerobic condition?
    2 years ago
  • kaari
    What is the fate of pyruvate under aerobic conditions?
    2 years ago
  • BEATO BUCCHO
    What are the fate of pyruvate under anaerobic conditions?
    1 year ago
  • Lawana
    What happena to pyruvate under anaerobic condition?
    1 year ago
  • selma
    What happen to pyruvate under anaerobic condition ethanol and fermentation?
    1 year ago
  • Christina
    What is the fate of pyruvic acid in anaerobic?
    1 year ago
  • klaudia frei
    What is the fate of pyruvate under anaerobic respiration?
    1 year ago
  • nilde
    What is the fate of pyruvate under aerobic and anaerobic conditions?
    1 year ago
  • MAIK
    What are the fates of pyruvate under anaerobic respiration?
    8 months ago

Post a comment