tejsavképzés

Tejsavképzés, also known as lactic acid fermentation, is a metabolic process that converts pyruvate into lactate. This process occurs in the absence of oxygen, hence it is classified as anaerobic respiration. Tejsavképzés is a crucial pathway for many microorganisms, including bacteria and yeasts, and also plays a role in the metabolism of certain animal cells, particularly muscle cells during intense physical activity.

In this biochemical pathway, the enzyme lactate dehydrogenase catalyzes the reduction of pyruvate, a product of glycolysis, to lactate. This reaction simultaneously oxidizes NADH to NAD+, which is essential for the continuation of glycolysis. Glycolysis is the initial stage of glucose metabolism that produces ATP, the energy currency of the cell. By regenerating NAD+, tejsavképzés allows glycolysis to proceed even when oxygen is unavailable to act as the final electron acceptor in the more efficient aerobic respiration pathway.

Different types of tejsavképzés exist, broadly categorized into homolactic fermentation, where lactate is the sole product, and heterolactic fermentation, which yields lactate along with other products like ethanol or acetate. Homolactic fermentation is common in bacteria like *Lactobacillus* species, which are vital in the production of dairy products such as yogurt and cheese, and in human muscle cells. Heterolactic fermentation is carried out by other bacteria and some yeasts.

The accumulation of lactic acid can contribute to muscle fatigue during strenuous exercise. However, in many organisms, lactate can be transported to other tissues, such as the liver, where it can be converted back to pyruvate and re-enter aerobic metabolism (the Cori cycle). This process highlights the interconnectedness of metabolic pathways within an organism.