Anaerobic respiration refers to the oxidation of molecules in the absence of oxygen to produce energy, in opposition to Aerobic respiration which does use oxygen. Anaerobic respiration processes require another electron acceptor to replace oxygen. Anaerobic respiration is often used interchangeably with fermentation, especially when the glycolytic pathway is used for energy production in the cell. They are not synonymous terms, however, since certain anaerobic prokaryotes can generate all of their ATP using an electron transport system and ATP synthase. The word & symbol equation for the anaerobic respiration of glucose is: General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... This article or section should be merged with aerobic metabolism. ... e- redirects here. ... This article or section does not cite its references or sources. ... Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ... Prokaryotes (pro-KAR-ee-oht) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ...

Glucose Lactic acid + Energy (ATP) Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Lactic acid (IUPAC systematic name: 2-hydroxypropanoic acid), also known as milk acid, is a chemical compound that plays a role in several biochemical processes. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ...

C₆H₁₂O₆ 2C₃H₆O₃ + 2 ATP

The energy released is about 120kJ per mole Glucose.

Obligate Anaerobes

In some organisms called obligate (strict) anaerobes (ex: C. tetani (causes tetanus), C. perfringens (causes gangrene)), the presence of oxygen is lethal. This is because the presence of oxygen is processed by the organisms into the extremely toxic molecules of single oxygen (¹O₂), superoxide ion (O₂^-), hydrogen peroxide (H₂O₂), hydroxyl ion (OH^-), and other toxic molecules An anaerobic organism or anaerobe is any organism that does not require oxygen. ... Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. ... Gangrene is necrosis and subsequent decay of body tissues caused by infection or thrombosis or lack of blood flow. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... “Multivalent” redirects here. ... Hydrogen peroxide (H2O2) is a very pale blue liquid which appears colourless in a dilute solution, slightly more viscous than water. ... “Multivalent” redirects here. ...

Faculative Anaerobes and Obligate Aerobes

Faculative anaerobes (organisms that can survive in either oxygenated or deoxygenated environments and can switch between cellular respiration or fermentation, respectively) and obligate (strict) aerobes (organisms that can survive only with oxygen) have special enzymes (superoxide dimutase and catalase) that can safely handle these products and transform them into harmless water and diatomic oxygen in the following reactions: An aerobic organism or aerobe is an organism that has an oxygen based metabolism. ...

1. 2O₂^- + 2H⁺ ---Superoxide Dismutase--> H₂O₂ (hydrogen peroxide) + O₂

The hydrogen peroxide produced is then transferred to a second reaction...

2. 2H₂O₂ ---Catalase--> 2H₂O + O₂

The oxidative powers of the superoxide ion have now been neutralized. Only faculative anaerobes and obligate aerobes possess the two enzymes necessary to reduce the superoxide.

In organisms which use glycolysis, the absence of oxygen prevents pyruvate from being metabolised to CO₂ and water via the citric acid cycle and the electron transport chain (which relies on O₂) does not function. Fermentation does not yield more energy than that already obtained from glycolysis (2 ATPs) but serves to regenerate NAD⁺ so glycolysis can continue. Various end products can also be created, such as lactate or ethanol. Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ... Pyruvate (CH3COCOO−) is the ionized form of pyruvic acid. ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Overview of the citric acid cycle The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle, after Hans Adolf Krebs who identified the cycle) is a series of chemical reactions of central importance in all living cells that use oxygen as part... The Electron Transport Chain. ... Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ... Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ... Lactic acid is a chemical compound that plays a role in several biochemical processes. ... Ethanol, also known as ethyl alcohol, drinking alcohol or grain alcohol, is a flammable, colorless, slightly toxic chemical compound with a distinctive perfume-like odor, and is the alcohol found in alcoholic beverages. ...

Fermentation in animals is essential to human life.

In lactic acid fermentation, the following reaction occurs:

1. Glycolysis C₆H₁₂O₆ (glucose) + 2 NAD⁺ 2 C₃H₄O₃ (pyruvic acid) + 2 NADH Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ...

2. Lactic Acid Creation 2 C₃H₄O₃ (pyruvic acid) + 2 NADH 2 C₃H₆O₃ (lactic acid) + 2 NAD⁺ Lactic acid (IUPAC systematic name: 2-hydroxypropanoic acid), also known as milk acid, is a chemical compound that plays a role in several biochemical processes. ...

Net Reaction: C₆H₁₂O₆ (glucose) 2 C₃H₆O₃ (lactic acid)

Fermentation in other organisms

In some plant cells and yeasts, fermentation produces CO₂ and ethanol. The conversion of pyruvate to acetaldehyde generates CO₂ and the conversion of acetaldehyde to ethanol regenerates NAD⁺. Pyruvate (CH3COCOO−) is the ionized form of pyruvic acid. ... R-phrases , , S-phrases , , , Flash point −39 °C Autoignition temperature 185 °C RTECS number AB1925000 Supplementary data page Structure and properties n, εr, etc. ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... Ethanol, also known as ethyl alcohol, drinking alcohol or grain alcohol, is a flammable, colorless, slightly toxic chemical compound with a distinctive perfume-like odor, and is the alcohol found in alcoholic beverages. ... Space-filling model of NADH Nicotinamide adenine dinucleotide (NAD+) is an important coenzymes found in cells. ...

Anaerobic respiration in prokaryotes

In the field of prokaryotic metabolism, anaerobic respiration has a more specific meaning. In this case, anaerobic respiration is defined as a membrane bound biological process coupling the oxidation of electron donating substrates (e.g. sugars and other organic compounds, but also inorganic molecules like hydrogen, sulfide/sulfur, ammonia, metals or metal ions) to the reduction of suitable external electron acceptors other than molecular oxygen. In contrast, in fermentation the oxidation of molecules is coupled to the reduction of an internally-generated electron acceptor, usually pyruvate. Hence, scientists who study prokaryotic physiology view anaerobic respiration and fermentation as distinct processes and therefore do not use the terms interchangeably. This article or section does not cite its references or sources. ...

In anaerobic respiration, as the electrons from the electron donor are transported down the electron transport chain to the terminal electron acceptor, protons are translocated over the membrane from "inside" to "outside", establishing a concentration gradient across the membrane which temporarily stores the energy released in the chemical reactions. This potential energy is then converted into ATP by the same enzyme used during aerobic respiration, ATP synthase. Possible electron acceptors for anaerobic respiration are nitrate, nitrite, nitrous oxide, oxidised amines and nitro-compounds, fumarate, oxidised metal ions, sulfate, sulfur, sulfoxo-compounds, halogenated organic compounds, selenate, arsenate, bicarbonate or carbon dioxide (in acetogenesis and methanogenesis). All these types of anaerobic respiration are restricted to prokaryotic organisms. The Electron Transport Chain. ... This article or section should be merged with aerobic metabolism. ... An ATP synthase (EC 3. ...

Examples of anaerobic respiration:

Glucose + 3NO₃^- + 3H₂O 6HCO₃^- + 3NH₄⁺, ΔG⁰' = -1796 kJ

Glucose + 3SO₄^2- + 3H⁺ 6HCO₃^- + 3NH^-, ΔG⁰' = -453 kJ

Glucose + 12S + 12H₂O 6HCO₃^- + 12HS^- + 18H⁺, ΔG⁰' = -333 kJ

All of these terminal electron acceptors are further upstream in the electron transport chain, compared to O₂. Consequently, anaerobic respiration is less effective than aerobic respiration. The ΔG⁰' of aerobic respiration is -2844 kJ.

Commercial applications of anaerobic respiration

• Anaerobic digestion
• Mechanical biological treatment

v • d • e Metabolism map

A few of the metabolic pathways in a cell. ... Image File history File links Metabolism_790px_partly_labeled. ... Glucuronate metabolism Pentose interconversion Inositol metabolism Cellulose and sucrose metabolism Starch and glycogen metabolism Other sugar metabolism Pentose phosphate pathway Glycolysis and Gluconeogenesis Amino sugars metabolism Small amino acid synthesis Branched amino acid synthesis Purine biosynthesis Histidine metabolism Aromatic amino acid synthesis Pyruvate decarboxylation Anaerobic respiration Fatty acid metabolism Urea cycle Aspartate amino acid group synthesis Porphyrins and corrinoids metabolism Citric acid cycle Glutamate amino acid group synthesis Pyrimidine biosynthesis  v • d • e  All pathway labels on this image are links, simply click to access the article. A high resolution labeled version of this image is available here.