Is Carbon Dioxide Released in Fermentation of Pyruvic Acid to Lactic Acid?

Glycolysis is the pathway of respiration (converting glucose into pyruvate) that is conducted in the absence of oxygen. and fermentation is the final step of the glycolysis. This process yields two net ATPs (adenosine triphosphate); these are considered the energy currency of the cell. Fermentation in plant cells yields ethyl alcohol and carbon dioxide from pyruvic acid. In animal and bacterial cells, pyruvic acid ferments to lactic acid. Carbon dioxide is not produced as a primary or secondary product.

Glycolysis

• The pathway of glycolysis happens in all types of cells. In all cells, the pathway is the same until the last step of fermentation occurs.

Animal Cells

• Fermentation in animal cells results in pyruvic acid being converted to lactic acid in the body. This is evidenced in tired muscles and the pain that comes with it. Lactic acid buildup is responsible for it.

Bacterial Cells

• In bacteria, fermentation converts pyruvic acid to an intermediate called acetalaldehyde. It's eventually converted to lactic acid.

Industry Use

• Cheese is produced by fermentation. Specifically, the sugar from milk is fermented to lactic acid. Then, the enzyme rennet is added. Yogurt is a product of bacterial fermentation, and lactic acid gives yogurt its distinct taste.

Considerations

• Carbon dioxide is a product of aerobic respiration in the presence of oxygen. The pathway of the citric acid cycle eventually produces the bulk of ATPs used by the body.