Aerobic organism

Aerobic organism

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An aerobic organism or aerobe is an organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...

 that can survive and grow in an oxygenated environment.
Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.

Glucose


A good example would be the oxidation of glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 (a monosaccharide
Monosaccharide
Monosaccharides are the most basic units of biologically important carbohydrates. They are the simplest form of sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose , fructose , galactose, xylose...

) in aerobic respiration.
C6H12O6 + 6 O2 + 38 ADP
Adenosine diphosphate
Adenosine diphosphate, abbreviated ADP, is a nucleoside diphosphate. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase adenine....

 + 38 phosphate → 6 CO2 + 6 H2O + 38 ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...



Notice that oxygen is used during the oxidation of glucose and water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 is produced.

This equation is a summary of what actually happens in three series of biochemical reactions: glycolysis
Glycolysis
Glycolysis is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+...

, the Krebs cycle, and oxidative phosphorylation
Oxidative phosphorylation
Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate . Although the many forms of life on earth use a range of different nutrients, almost all aerobic organisms carry out oxidative phosphorylation to produce ATP,...

.

Diversity


Almost all animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s, most fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

, and several bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 are obligate aerobes, which require oxygen. Most anaerobic organism
Anaerobic organism
An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present...

s are bacteria. Being an obligate aerobe, although advantageous from the energetical point of view, also means obligatory exposure to high levels of oxidative stress
Oxidative stress
Oxidative stress represents an imbalance between the production and manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage...

.

Yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

 is an example of a facultative anaerobe, which can develop in the presence of oxygen but does not require it. Individual human cells are also facultative anaerobes: they switch to lactic acid
Lactic acid
Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3...

 fermentation
Fermentation (biochemistry)
Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...

 if oxygen is not available. However, for the whole organism this cannot be sustained for long, and humans are therefore obligate aerobes.

See also

  • Aerobic digestion
  • Anaerobic digestion
    Anaerobic digestion
    Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. It is used for industrial or domestic purposes to manage waste and/or to release energy....

  • Facultative anaerobic organism
    Facultative anaerobic organism
    A facultative anaerobic organism is an organism, usually a bacterium, that makes ATP by aerobic respiration if oxygen is present but is also capable of switching to fermentation...

  • Fermentation (biochemistry)
    Fermentation (biochemistry)
    Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...

  • Microaerophile
    Microaerophile
    A microaerophile is a microorganism that requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere . Many microphiles are also capnophiles, as they require an elevated concentration of carbon dioxide. In the laboratory they can be...