Question

prepare an article on anaerobic respiration to present school symposium

Answer 1

Anaerobic respiration is a form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain called physolmere; it is respiration without oxygen.[1]

In aerobic organisms undergoing respiration, electrons are shuttled to an electron transport chain, and the final electron acceptor is oxygen. Molecular oxygen is a highly oxidizing agent and, therefore, is an excellent acceptor. In anaerobes, other less-oxidizing substances such as sulfate (SO42−), nitrate (NO3−), sulphur (S), or fumarate are used. These terminal electron acceptors have smaller reduction potentials than O2, meaning that less energy is released per oxidized molecule. Anaerobic respiration is, therefore, in general energetically less efficient than aerobic respiration.

Anaerobic respiration is used mainly by bacteria and archaea that live in environments devoid of oxygen. Many anaerobic organisms are obligate anaerobes meaning that they can respire only using anaerobic compounds and will die in the presence of oxygen.

Anaerobic respiration as compared with fermentation

Cellular respiration (both aerobic and anaerobic) utilizes highly reduced chemical compounds such as NADH and FADH2 (for example produced during glycolysis and the citric acid cycle) to establish an electrochemical gradient (often a proton gradient) across a membrane, resulting in an electrical potential or ion concentration difference across the membrane. The reduced chemical compounds are oxidized by a series of respiratory integral membrane proteins with sequentially increasing reduction potentials with the final electron acceptor being oxygen (in aerobic respiration) or another chemical substance (in anaerobic respiration). A proton motive force or pmf drives protons down the gradient (across the membrane) through the proton channel of ATP synthase. The resulting current drives ATP synthesis from ADP and inorganic phosphate.

Fermentation, in contrast, does not utilize an electrochemical gradient. Fermentation instead only uses substrate-level phosphorylation to produce ATP. The electron acceptor NAD+ is regenerated from NADH formed in oxidative steps of the fermentation pathway by the reduction of oxidized compounds. These oxidized compounds are often formed during the fermentation pathway itself, but may also be external. For example, in homofermentative lactic acid bacteria, NADH formed during the oxidation of glyceraldehyde-3-phosphate is oxidized back to NAD+ by the reduction of pyruvate to lactic acid at a later stage in the pathway. In yeast, acetaldehyde is reduced to ethanol to regenerate NAD+. The two processes thus generate ATP in very different ways, and the terms should not be treated as synonyms.

Answer 2

Anaerobic respiration is a procedure which produce energy when O₂ is not present. Anaerobic respiration is the way in which glucose(C₆H₁₂O₆) is broken down into molecules without O₂ to produce energy. The first step in all pathways of cell respiration is glycolysis without molecular O₂. In case of low O₂ supply, various eukaryotic cells switch their anaerobic respiration process.

When we exercise our body response to the working muscles by supplying more O₂. In presence of O₂, the glucose(C₆H₁₂O₆) broke into CO₂ and H₂O. But when we follow irrelevant activities, the O₂ level become decreases  in the muscle tissue. This low level of O₂ results in anaerobic respiration in the cell and lactic acid is developed to provide the much required ATP molecules for cellular functions. This makes our muscles tired and may cramps.