What is aerobic breathing 3



As part of the Dissimilation energy stores created by an organism (for example fats or the carbohydrates starch or glycogen) are broken down, whereby energy is released. This can be used as ATP and / or heat.

Dissimilations are reactions of the catabolic metabolism.

One distinguishes breathing (aerobic) and fermentation (anaerobic).

In the breathing substrates are oxidized. The electrons released in the process are transferred to external electron acceptors via the respiratory chain.

  • In the aerobic breathing serves oxygen (O2 ) as an electron acceptor. It occurs in all aerobic organisms and provides most of the energy (free enthalpy). The substrate turns completely into CO2 and water degraded.
  • In the anaerobic breathing serve nitrate (NO3-), Fumarate, Fe3+ or sulfate (SO42-) as electron acceptors.

Fermentations take place when no respiratory chain or no external electron acceptor is available. Internal acceptors, such as the pyruvate, acetyl-CoA or oxonium ions produced by glycolysis, then serve as electron acceptors. The degradation of the substrate is mostly incomplete, the degradation products are excreted. The ATP yield is relatively low and is around 2 to 4 ATP / substrate

Word explanation

Dissimilation comes from Latin dissimilisi.e. dissimilar. In contrast to assimilation (biology) (lat. assimilatio = Approximation): Here, exogenous organic or inorganic substances absorbed from the environment become the body's own. During dissimilation, these substances become foreign substances again, which are excreted.

Cellular respiration

Cell respiration can be broken down into 4 steps:

In the following, the steps are to be carried out individually.

  • Glycolysis:
    • The glucose is a reaction carrier and must first be phosphorylated with 2 ATP.
    • With 2 energy-supplying steps 4 ATP are released
    • Hydrogen is obtained in the form of 2 molecules of NADH / H +
    • There remains pyruvic acid, it is still very rich in energy
  • Oxidative decarboxylation
    • The pyruvic acid becomes acetic acid with the release of carbon dioxide, and an NAD becomes NADH / H +
    • The acetic acid is "activated" by the coenzyme A and is then called activated acetic acid or acetyl-coenzyme A.
    • In this way, 4 or 3 NADH / H + are obtained from a C3 body
  • Citric Acid Cycle
    • The activated acetic acid is broken down into two carbon dioxide. The hydrogen passes over to two reduced coenzymes (NADH / H + and FADH / H +)
    • It starts when the activated acetic acid binds to oxaloacetic acid (C4). The resulting product is citric acid. The citric acid cycle is also called the tricarboxylic acid cycle.

See also

assimilation

Category: Metabolism