Anaerobic Respiration

Respiration is a chemical reaction that occurs in every one of the cells in the human body and all cells on the entire planet. Remember, respiration is not the same as breathing. The scientific name for breathing is ‘ventilation’.

Respiration releases energy stored in glucose and without it, these cells would die. There are two types of respiration:

• Aerobic respiration occurs in the presence of oxygen and most cells most of the time.
• Anaerobic respiration occurs without oxygen and much less frequently than aerobic respiration.

Human bodies use both types of respiration. Humans do aerobic respiration unless they are short of oxygen when they switch to anaerobic respiration.

What is anaerobic respiration?

An anaerobic process in which organic food is converted into simpler compounds, and chemical energy (ATP) is produced. Certain types use the electron transport chain system to pass the electrons to the final electron acceptor, which may be an inorganic or an organic compound, but not oxygen.

Anaerobic vs. Aerobic Respiration vs. Fermentation:

Anaerobic stands for “without oxygen.” This method of cellular respiration does not require oxygen to generate energy. For smaller animals to breathe, there is not enough oxygen available so they need the energy to survive in the absence of oxygen. They carry out respiration to produce the energy they need, which is referred to as anaerobic respiration. That is in contrast to aerobic respiration that requires oxygen, which serves as the final electron acceptor in the electron transport chain system.

In fermentation, this step is skipped. After glycolysis, pyruvate (in lactic acid fermentation) or acetaldehyde (in alcohol fermentation) serves as the final electron acceptor. In this process, the energy from glucose is converted into another form that can be used by the cell or stored for later use.  It produces lactic acid instead of carbon dioxide and water. This type of respiration is only used for short intervals.

Process of Anaerobic Respiration:

The first step of anaerobic respiration is glycolysis, in which a glucose molecule is broken down into two pyruvate molecules, releasing electrons in the process and producing two ATP molecules, the energy of the cells. As oxygen is present during aerobic respiration, some pyruvate molecules go through two other stages that serve to release more electrons, later used to power a very high amount of ATP production. But when, as in the case of fermentation, oxygen is absent, the last two stages are bypassed. Instead, pyruvate is converted into a different byproduct, and carbon dioxide is released as well. In this process, two ATP molecules are produced.

Where does anaerobic respiration occur?

In the fluid part of the cytoplasm, anaerobic respiration (both glycolysis and fermentation) takes place, while the majority of the energy production in aerobic respiration takes place in the mitochondria.

Anaerobic respiration Equations:

• Fermentation:

                   C6H12O6 → C2H5OH + CO2 + energy

• Lactic acid fermentation equation:

                  C6H12O6 → 2CO2 + 2C2H6O + 2ATP

Anaerobic respiration formula:

• Denitrification: NO3− → NO2−→ NO + N2O → N2 
• Methanogenesis: (1) CO2 + 4 H2 → CH4 + 2 H2O, (2)
• CH3COOH → CH4 + CO2
• Anaerobic respiration in humans:  glucose → lactic acid
• Anaerobic Respiration in bacteria and Fungi:  glucose → ethanol + carbon dioxide

Functions of Anaerobic Respiration:

All living organisms undergo cellular respiration. In certain types of bacteria and yeast, anaerobic respiration is preferred. It gives them the advantage of surviving or thriving in an anoxic environment that would be lethal to aerobic organisms.

Anaerobic respiration also has a very high speed. It produces ATP very rapidly. Aerobic respiration, on the other hand, produces ATP rather slowly.

Difference Between Aerobic and Anaerobic Respiration:

The primary difference between aerobic and anaerobic respiration is the presence or absence of oxygen during the processes. More detailed differences are between the two are as follows:

Conclusion:

The fundamental difference between aerobic and anaerobic respiration is the usage of oxygen in the process of cellular respiration. Aerobic respiration, as the name suggests, is the process of producing the energy required by cells using oxygen. The by-product of this process produces carbon dioxide along with ATP – the energy currency of the cells. Anaerobic respiration is similar to aerobic respiration, except, the process happens without the presence of oxygen. Consequently, the by-products of this process are lactic acid and ATP.