How do fermentation and anaerobic respiration differ?

1 Answer

Fermentation and anaerobic respiration differ because although they both start with glycolysis, fermentation does not stop with the product of glycolysis, but instead creates pyruvate and continues on the same path as aerobic respiration.


Adenosine Triphosphate (ATP) is the chemical form of energy . There are many different mechanisms that can convert the original energy source into ATP. The most efficient way is through aerobic respiration, which requires oxygen. This method will give the most ATP per input energy source. However, if no oxygen is available, the organism must still convert the energy using other means. Processes that happen without oxygen are called anaerobic. Fermentation is a common way for living things to continue making ATP without oxygen.

Aerobic respiration begins with a process called glycolysis. In glycolysis, a carbohydrate (such as glucose) gets broken down and, after losing some electrons, forms a molecule called pyruvate. If there is a sufficient supply of oxygen, or sometimes other types of electron acceptors, the pyruvate then goes on to the next part of aerobic respiration. The process of glycolysis will make a net gain of 2 ATP.

Fermentation is essentially the same process. The carbohydrate gets broken down, but instead of making pyruvate, the final product is a different molecule depending on the type of fermentation. (due to lack of oxygen) In Humans Instead of pyruvate, lactic acid is formed. Long distance runners are familiar with lactic acid. It can build up in the muscles and cause cramping.. Since fermentation does not use the electron transport chain, it is not considered a type of respiration.

Anaerobic respiration begins the same way as aerobic respiration and fermentation. The first step is still glycolysis and it still creates 2 ATP from one carbohydrate molecule. However, instead of just ending with the product of glycolysis it will create pyruvate and then continue on the same path as aerobic respiration.

After making a molecule called acetyl coenzyme A, it continues on into the citric acid cycle. More electron carriers are made and then everything ends up at the electron transport chain. The electron carriers deposit the electrons at the beginning of the chain and then, through a process called chemiosmosis, . If the final electron acceptor is oxygen, the process is considered aerobic respiration. and like many types of bacteria and other microorganisms, can use different final electron acceptors. That is called anaerobic respiration.

Scientists believe that fermentation and anaerobic respiration are more ancient processes than aerobic respiration. Lack of oxygen in the early Earth's atmosphere made aerobic respiration impossible at first.