Describe the process of fermentation in detail.

Explanation

In fermentation by yeast, the incomplete oxidation of glucose is achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted to `CO_(2)` and ethanol .
`C_(6) H_(12) O_(6) to 2CH_(3)CO*CO O H to 2C_(2) H_(5) OH to 2CO_(2)`
The enzymes, pyruvic acid, decarboxylase and alcohol dehydrogenase catalyse these reactions .
Other organisms like some bacteria produce lactic acid from pyruvic acid .
In animal cells also, like muscles during exercise, when oxygen is inadequate for cellular respiration pyruvic acid is reduced to lactic acid by lactate dehydrogenase.
The reducing agent is `NADH + H^(+)` which is reoxidised to `NAD^(+)` in both the processes.
In both lactic acid and alcohol fermentation not much energy is release.
Less than 7% of the energy in glucose is released and not all of it is trapped as high energy bonds of ATP .
Also, the processes are hazardous.
In this synthesis 4 ATP are formed and 2 ATP are used means benefit of 2ATP occurs.
When the proportion of alcohol is more then 13% it becomes poisonous for yeast. It becomes the cause of its death .
In eukaryotes these steps take place within the mitochondria and this requires `O_(2)` . Aerobic respiration is the process that leads to a complete oxidation of organic substances in the presence of oxygen and releases `CO_(2)` water and a large amount of energy present in the substrate.