Aerobic Respiration

We explain what aerobic respiration is, how it is carried out and examples. Also, its different stages and anaerobic respiration.

Aerobic Respiration
Aerobic respiration takes place inside the cells of living things.

What is aerobic respiration?

It is known as aerobic respiration or aerobic respiration. a series of metabolic reactions that take place within the cells of living beings, through which chemical energy is obtained from the decomposition of organic molecules (cellular respiration).

It is about a complex process of obtaining energy which consumes glucose (C6H12O6) as fuel and oxygen as the final electron acceptor (oxidant) in reaction with pyruvic acid (C3H4O3). This results in carbon dioxide (CO2), water (H2O) and numerous quantities of Adenosine triphosphate (ATP), the biochemical energy molecule par excellence.

This process is typical of eukaryotes and certain forms of bacteria, and occurs according to the following formula: c6h12EITHER6+6O2→ 6CO2+ 6H2O + ATP.

See also: Types of breathing

Examples of aerobic respiration

Aerobic Respiration
Birds use their lungs to obtain oxygen from the air.

Some examples of aerobic respiration are:

  • The metabolism of humans, reptiles, birds and mammals in their entirety, which use their lungs to obtain oxygen from the air.
  • The metabolism of fish and other aquatic beings, which have gills to obtain oxygen from the water.
  • The metabolism of insects, which incorporate oxygen from the air through a series of tracheae throughout their body. Another case is worms and worms, which do the same thing through the skin (cutaneous respiration).

Stages of aerobic respiration

Aerobic respiration is a complex process that involves a series of steps in a long chemical reaction. These stages are:

  • Glycolysis. The initial step of aerobic respiration occurs in the cytoplasm of the cell and is the oxidation of glucose (and glycerol from triglycerides, if any). This process breaks the bonds of each molecule of this sugar and obtains in exchange two molecules of pyruvic acid, along with two molecules of ATP.
  • Oxidative decarboxylation of pyruvic acid. Pyruvic acid molecules enter the cytoplasm into the matrix of the mitochondria (energy organelles of the cell), where they are processed by a complex of enzymes (pyruvate dehydrogenase) that remove a carbon atom (decarboxylation), released as CO2, and then two hydrogen atoms (dehydrogenation). As a result, acetyl radicals (-CO-CH3) are obtained, which begins the next phase.
  • Krebs cycle. The last phase of respiration occurs in a metabolic cycle in the mitochondrial matrix, known as the Krebs Cycle. This begins with the acetyl from the previous phase, subjected to oxidation to produce two molecules of CO2 and energy in the form of Guanosyntriphosphate (GTP) and other usable reducing molecules.
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Then a chain of chemical reactions occurs that reoxidizes the enzymatic components reduced in the previous phase, making them available for new use, and obtaining new ATP in the process.

The latter already occurs in the inner membrane of the mitochondria. The electrons and protons released in the process are received by oxygen which is then reduced to water.

Anaerobic respiration

Anaerobic or anaerobic respiration is distinguished from aerobic respiration in one thing: the presence of oxygen. This type of cellular respiration consists of the oxidoreduction of monosaccharide sugars, using an element other than oxygen for oxidation: derivatives of nitrogen (nitrates), sulfur (sulfates and sulfides), carbon dioxide, iron or manganese ions, selenium (selenates), arsenic (arsenate), among others. These molecules are less effective and less energy is generated than using oxygen.

Anaerobic respiration is different from fermentation, and produces various substances as byproducts, depending on the element used as an electron acceptor. This metabolic mechanism It is typical of certain bacteria and prokaryotic microorganisms that inhabit oxygen-depleted environments.