Oxygen in living beings plays a highly relevant role, in many cases vital. Through the process known as respiration, oxygen allows a large number of organisms to stay alive (British & Journal, 2017).
Respiration consists of the metabolic reactions carried out by cells to obtain energy. Organisms that require oxygen for this purpose are known as Aerobes; those that don't are called Anaerobes.
Oxygen cycle
Oxygen is also an important part of the chemical structure of most components of living beings.
It is present in the most basic components such as carbohydrates, sugars, lipids and proteins.
Oxygen and energy in living beings
In aerobic organisms, oxygen is necessary for the respiratory process and obtaining energy.
However, for anaerobic organisms oxygen is not necessary and in many cases it is toxic.
Although oxygen is essential for the survival of aerobic organisms, it can also be harmful.
Usually the respiration process generates reactive oxygen molecules that act as toxic substances in a process known as oxidative stress and that deteriorates cells (Magenta, Dellambra, Ciarapica, & Capogrossi, 2016).
There are also organisms that, depending on environmental conditions, may or may not use oxygen to obtain energy. These organisms are known as facultative.
Oxygen, photosynthesis and food
The production of oxygen is closely linked to the production of food for many living things.
In photosynthesis, organisms that use light as an energy source produce organic compounds and oxygen (Caumette, Lebaron, & Matheron, 2011).
The organic compounds that are derived from photosynthesis are consumed by heterotrophic organisms, that is, those that do not produce their own food. In many cases these heterotrophic organisms also consume oxygen.
Without the presence of oxygen, the photosynthesis process would not take place as we know it and the food production of many living things could not take place.
Oxygen in evolution.
Oxygen has been the main responsible for the fact that life on earth is made up of the organisms that exist today. In addition, it has influenced the way they obtain their nutrients and energy (Packard, 2017)
The presence of large amounts of oxygen in the atmosphere prompted the proliferation of organisms that use oxygen to obtain energy. This selective pressure allowed the flora and fauna that today inhabit the planet to be established.
Evolutionarily, the presence of mitochondria in some living beings is attributed to an anaerobic cell with a nucleus that absorbed an aerobic cell.
The absorbed cell became the mitochondrion, allowing organisms such as humans to appear.
Oxygen promises to remain a decisive element in the evolution of life on earth.
Apart from the importance of its availability for food and the metabolism of living beings, its known role in the planet's climate will define the life forms that will survive (Decker & Kensal, 2011).
References
- British T. Breathing In Living Beings. BMJ. 2017; 1 (2254): 5–6.
- Caumette J. Lebaron P. Matheron R. (2011). Environmental Microbiology: Fundamentals and Applications.
- Decker H. Kensal E. Van H. (2011). Oxygen and the Evolution of Life. Springer.
- Magenta A. Dellambra E. Ciarapica R. Capogrossi M. Cell Calcium Oxidative stress, microRNAs and cytosolic calcium homeostasis. Cell Calcium. 2016; 60 (3), 207–217.
- Packard G. The Evolution of Air-Breathing in Paleozoic Gnathostome Fishes. Society for the Study of Evolution. 2017; 28 (2): 320–325.