Fermentation - incomplete oxidation of glucose

FERMENTATION 

Fermentation is the incomplete oxidation of glucose under the anaerobic conditions by the series  of reactions. 

Fermentation by yeast 

During the fermentation that occurs in yeast, pyruvic acid is converted into carbon dioxide and ethanol. The enzymes pyruvic acid decarboxylase and alcohol dehydrogenase are involved in reactions of fermentation. Various microbes like Bacteria and yeast are involved in fermentation.

Fermentation is a chemical process by which  the manufacture of wine and beer takes place. A French microbiologist Louis Pasteur used the term fermentation.

Fermentation by Muscle cell

But Some bacteria produce lactic acid from pyruvic acid during fermentation. In animal cells, pyruvic acid is also converted into lactic acid by fermentation. This process of fermentation takes place in muscles during exercise. When oxygen is deficient or muscles are fatigue during the exercise or more work  done by  the muscles, in these cases, pyruvic acid is reduced into lactic acid by lactate dehydrogenase. 

👌👌Remember The reducing agent is NADH2 which is  again oxidised into NAD+ in both the processes like  in fermentation of muscle cells and fermentation by bacteria.

In both fermentation  of lactic acid and  fermentation of ethanol,  not much energy is released.  Only less than seven per cent of the energy  is released and not trapped as high energy bonds of ATP.  The net ATPs synthesised when one molecule of glucose is fermented into alcohol or lactic acid is Two ATP Molecule. These two ATP are synthesised during glycolysis when glucose is converted into pyruvic acids.

The processes in which either acid or alcohol is produced,may be fatal or not beneficial for the health. Yeast fermentation may also cause death when the concentration of alcohol reaches about  thirteen per cent. The maximum concentration of alcohol in beverages that are naturally fermented would be also thirteen percent. 

It is regarded that the products of fermentation are not always Ethyl alcohol and lactic acids. Butyl alcohol, acetone and acetic acid  are also formed by the fermentation of  various bacteria.  Citric acid, gluconic acid, antibiotics, folic acids, and riboflavin are obtained from the   fermentation by mould. 

👌👌Remember Kreb cycle & electron transport systems  are the process by which organisms can carry out complete oxidation of glucose and extract the energy stored to synthesise a larger number of ATP molecules needed for cellular metabolism.

In eukaryotes these steps take place within the mitochondria and this requires O2 . Aerobic respiration is the process that leads to a complete oxidation of organic substances in the presence of oxygen, and releases CO2 , water and a large amount of energy present in the substrate. This type of respiration is most common in higher organisms.