Difference between Aerobic and Anaerobic Respiration

Respiration is a continuous process which occurs in the cells of all living organisms to produce energy. In this process, energy is released by breaking down glucose in the cells of the body. This energy is used in different body functions such as it is used by working muscles, chemical reactions, impulses which travel throughout the body and to maintain body temperature. Cellular Respiration is of two types: Aerobic and Anaerobic respiration. Let us see how aerobic respiration differs from anaerobic respiration.

Aerobic Respiration

It refers to cellular respiration in which glucose is broken down in the cells using oxygen or in the presence of oxygen to produce energy in the form of ATP (Adenosine Triphosphate). It commonly occurs in all multicellular organisms like plants, animals, humans and other mammals.

While breathing, we inhale air which contains oxygen. This oxygen is transported to all body tissues and cells through blood. When oxygen reaches cells, the glucose present in the cells is broken down into carbon dioxide, water and energy. The energy is used by our body to perform different body functions and to help us grow.

Aerobic respiration comprises three stages: glycolysis, Krebs cycle and electron transport chain. Its chemical equation is as follows:

Glucose (C6H12O6) + Oxygen (6O2) ? Carbon Dioxide 6CO2 + Water 6H2O + Energy (2,900 kJ/mol)

Anaerobic Respiration

Anaerobic means "without air". So, as the name suggests, the anaerobic respiration takes place in the absence of oxygen. It does not require oxygen to break down the glucose to produce energy. It usually occurs in the unicellular organisms like fungi, bacteria, protozoa and muscle cells. In this respiration, the glucose, which is derived from food, is broken down into alcohol, carbon dioxide and energy in the form of ATP. The energy produced in anaerobic respiration is less than aerobic respiration.

It usually occurs in tissues which often require more energy such as working muscles. These tissues don't get enough oxygen to produce required energy by breaking down the glucose through aerobic respiration so they have to carry out anaerobic respiration. It takes place in the cell cytoplasm and produces lactic acid.

Chemical equation: Glucose (C6H12O6) ? 2C3H6O3 (Lactic acid) + Energy

Based on the above information, some of the key differences between aerobic and anaerobic respiration are as follows:

Aerobic Respiration	Anaerobic Respiration
It occurs in the presence of oxygen (requires oxygen).	It occurs in the absence of oxygen (does not require oxygen).
The end products include carbon dioxide and water with energy (ATP molecules). It always produces CO2 and H2O.	The end products include carbon dioxide, ethanol or lactic acid and energy (ATP). The end products may vary.
It occurs in multicellular organisms like plants, animals, humans etc.	It generally occurs in unicellular organisms like bacteria, fungi, protozoa etc.
It occurs in multicellular organisms like plants, animals, humans etc.	It generally occurs in unicellular organisms like bacteria, fungi, protozoa etc.
A large amount of energy is released in aerobic respiration. It generates 36 ATP molecules per glucose molecule.	Amount of energy released in anaerobic respiration is less, only 2 ATP molecules are produced per glucose molecule.
It occurs in the cytoplasm as well as in mitochondria in the cell.	It generally occurs in the cytoplasm.
It comprises three stages: glycolysis, Krebs cycle and electron transport chain.	It mainly comprises two states: glycolysis and fermentation.
Reactants include glucose and oxygen	Reactants are glucose and electron acceptor excluding oxygen
It is non-toxic to the organisms.	It is toxic to higher organisms.
The substrate is oxidized completely into carbon dioxide and water.	The substrate (glucose) is oxidized incompletely.
Chemical Equation: C6H12O6 + 6O2 ? 6CO2 + 6H2O + Energy (2,900 kJ/mol)	Chemical Equation: C6H12O6 ? 2C3H6O3
It involves the exchange of gases.	The exchange of gases does not occur.