• What is anaerobic respiration?
• Types of anaerobic respiration
• Examples of anaerobic respiration
• Glycolysis

We explain what anaerobic or anaerobic respiration is in biology, what types exist and examples of regions where it occurs.

Anaerobic respiration is unique to prokaryotic organisms, such as bacteria.

What is anaerobic respiration?

In biology, is called anaerobic respiration or anaerobic respiration when metabolic process from oxidoreduction of sugars. In other words, in this process glucose is oxidized to obtain Energy, without the presence of oxygen. That is, a process of cellular respiration in which oxygen molecules do not intervene.

Anaerobic respiration differs from aerobic respiration or aerobic since the latter requires oxygen to process the sugar molecules. On the contrary, anaerobic uses another type of chemical elements or even molecules more complex organic substances, through an electron transport chain.

Nor should it be confused with fermentation, since the conveyor chain does not intervene in it. electrons. However, both processes have in common that they occur in the absence of oxygen.

This type of cellular respiration is unique to certain prokaryotic organisms (bacteria or archaea), especially those that live in conditions of little or no oxygen presence. However, in many cases it can also constitute a secondary process, let's say an emergency, given the unexpected shortage of this element in the environment.

Types of anaerobic respiration

Anaerobic respiration can be classified according to the type of chemical element used to replace oxygen, that is, as an electron receptor during the metabolic process. Thus, there may be many types of processes of this nature, but the main and most common are:

• Anaerobic respiration through nitrates. In this case the microorganisms they consume nitrates (NO3–) to reduce them to nitrites (NO2–) by incorporating electrons into them. However, since nitrites are usually toxic to most forms of life, it is much more common for the end product of this process to go further, to biatomic nitrogen (N2), which is an inert gas. This process is known as denitrification.
• Anaerobic respiration through sulfates. Similar to the previous case, but with sulfur derivatives (SO42-), it is a much rarer case, belonging to totally anaerobic bacteria, while the previous case can occur as an alternative to the momentary shortage of oxygen. In this sulfate reduction process, sulfur radicals (S2-) are by-produced.
• Anaerobic respiration by carbon dioxide. Some groups of archaea that produce methane gas (CH4) consume carbon dioxide (CO2) to use it as an electron receptor. Of this nature are the microorganisms that inhabit the digestive tract of ruminants, for example, where other microorganisms supply them with the hydrogen they require for the process.
• Anaerobic respiration through iron ions. The latter case is common among certain bacteria, capable of consuming ions ferric (Fe3 +), reducing them to ferrous ions (Fe2 +), since this type of iron molecules are very common in the Earth crust. This is what happens at the bottom of swamps, where important iron sediments are produced by bacterial action.

Examples of anaerobic respiration

Organisms that live in hot springs perform anaerobic respiration.

Examples of this type of process are common in the prokaryotic world, especially in regions the most inhospitable of the planet, but not for that devoid of life. Such regions are:

• The intestines of higher animals.
• The seabed and abyssal crevices.
• The geothermal locks through which magma gushes to the bottom of the sea.
• Geysers, hot springs and other forms of geothermal outbreak.
• The swamps and clayey waters, full of organic material and low oxygen.

Glycolysis

Glycolysis or glycolysis is the metabolic route that allows obtaining Energy of glucose. In other words, it is a successive series of biochemical reactions, applied by most of the living beings, to break the glucose molecule (C6H12O6) and obtain from it the chemical energy necessary (in the form of ATP) to keep the metabolism cell phone.

Glycolysis consists of 10 reactions enzymatic that occur consecutively, either in the presence (aerobic) or in the absence (anaerobic) of oxygen. Results in the formation of two molecules of pyruvate or pyruvic acid (C3H4O3), which feed other metabolic pathways to continue obtaining energy for the organism (the so-called Krebs Cycle).