Question

What are the possible fates of pyruvic acid in the body?

Answer 1

Pyruvic acid:

1. Glycolysis is a common pathway that occurs in both aerobic and anaerobic modes of respiration.
2. It is the first step of glucose breakdown and is shared by all organisms.
3. It occurs in the cytosol and converts glucose or a similar hexose sugar into two molecules of pyruvic acid, a three-carbon compound, by releasing some energy and reducing power.
4. Pyruvate is an important molecule found at the crossroads of many biochemical pathways.
5. Both aerobic and anaerobic respiration share a set of initial steps known as glycolysis. During glycolysis, carbohydrates are converted into pyruvic acid via a series of enzymatic reactions.
6. There are three major pathways in the body that can use the pyruvic acid produced by glycolysis.
   1. Alcoholic Fermentation: It is found in fungi and bacteria. If the fungus is not in contact with the environment, pyruvate is first decarboxylated using the enzymes pyruvate decarboxylase, transacetylase, Mg⁺, and TPP. Acetaldehyde and carbon dioxide are produced with the help of pyruvic acid.
   2. Lactic Acid Fermentation: It is found in lactic acid bacteria as well as muscles. NADH2 reduces pyruvic acid produced during glycolysis to form lactic acid.
   3. Aerobic Respiration: Molecular oxygen serves as the ultimate acceptor of electrons and protons removed from the substrate during aerobic respiration. Pyruvic acid produced in the cytosol is transported to mitochondria, kicking off the second phase of respiration. Before pyruvic acid enters the Krebs cycle, which operates in the mitochondria, one of its three carbon atoms is oxidised to carbon dioxide in a process known as oxidative decarboxylation.