Aerobic respiration is also called aerobic respiration.It is called aerobic respiration when oxygen in the atmosphere is used for oxidation.Organisms that breathe aerobically must absorb free oxygen from the atmosphere to oxidize organic substances in the body and release energy.Aerobic respiration is a complex form of respiration.
Animals and plants carry out aerobic respiration day and night, but plants doassimilationthanAlienationIt is much stronger, so it releases much more oxygen during the day than it absorbs.[1]
majorityAerobic bacteriaIt breathes on glucose.Glucose is generally degraded into pyruvate through glycolysis, and pyruvate is further oxidized through the tricarboxylic acid cycle.[2]
Aerobic respiration, also known as aerobic respiration, refers to the complete oxidation and decomposition of glucose and other organic substances by cells with the participation of oxygen through the catalytic action of enzymescarbon dioxideAnd form water, release a lot of energy at the same time, and generate a lot of ATP, but another form of aerobic respiration is a direct oxidation pathway, that isFlavoproteinHorizontal breathing.This oxidation reaction does not generate ATP, so the energy is not used, but dissipated in the form of heat.[2]
characteristic
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Aerobic respiration is a biological oxidation process with molecular oxygen as the final electron acceptor.Many microorganisms can use various organic substances as oxidation substrates for aerobic respiration to obtain energy.[3]
Aerobic microorganisms have relatively complete respiratory enzyme systemdehydrogenase、oxidaseandCytochromeTherefore, molecular oxygen can be used to complete oxidation, and molecular oxygen can be used as hydrogen acceptor.[4]
The process of aerobic respiration is complicated.In short, the process of respiration is alsodehydrogenasesendstromaDehydrogenation oxidation (removal of activated hydrogen and electrons), 1 electron passing throughCytochromeAt last, the activated hydrogen combines with the molecular oxygen activated by oxidase to reduce oxygen and complete the whole respiratory process.
The aerobic breathing process can be represented by the following figure:
The final stage of aerobic respiration is the reduction of oxygen to water or hydrogen peroxide.hydrogen peroxideIt is a toxic substance to microorganisms, which must be removed when it accumulates to a certain extent.Aerobic microorganisms contain nitroperoxidase andPeroxidase，catalaseIt can decompose hydrogen peroxide into water and molecular oxygen. Peroxidase can activate the oxygen of hydrogen peroxide to oxidize other substrates and generate water, which relieves the toxicity of hydrogen peroxide, which is the detoxification effect of aerobic microorganisms.
Aerobic respiration, due to the complete oxidation of general matrix until it becomes COtwoAnd HtwoO，Therefore, much more energy is released than anaerobic respiration.However, there are a few aerobic microorganisms that can not completely oxidize the substrate in the process of respiration, and often only oxidize to formOrganic acidPhase of.[4]
Aerobic respiration stage
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According to the process of aerobic respiration, aerobic respiration can be divided into three stages:
① Stage I (glycolysis)
Various energy substances are converted intoAcetyl CoA, atCytoplasmic matrixMedium, 1 molecularglucoseDecomposed into two moleculespyruvic acidAt the same time, remove 4 [H], release a small amount of energy, synthesize 2 ATP, and dissipate the rest with heat energy.
② Phase II (tricarboxylic acid cycle/citric acid cycle)
Acetyl CoADicarboacetyl group of, converted to CO through tricarboxylic acid cycletwoAnd hydrogen atoms.Location:Mitochondrial matrix2 molecules of pyruvic acid and 6 molecules of hydrogen in water.That is, all 20 [H] are removed to generate 6 molecules ofcarbon dioxide, release a small amount of energy, synthesize 2 ATP, and the rest is lost in the form of heat energy.
③ Stage 3 (electron transfer chain/oxidative phosphorylation)
respiratory chainIt refers to the directional and orderly transfer system of electrons (hydrogen) removed from glucose or other compounds through a series of electron (hydrogen) carriers arranged from low to high according to the redox potential.Hydrogen atom entryElectron transfer chain(respiratory chain), which is finally transferred to oxygen and generates water with it. At the same time, ATP molecules are generated through the oxidative phosphorylation accompanying the electron transfer process. The site isMitochondrial intima24 [H] and 6 removed in the first two stagesOxygen moleculeCombine into water and release a lot of energy to synthesize 34 ATP.[5]
Research and application
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Aerobic respiration is the most common and important biological oxidation mode and the main production mode among microorganisms.Decompose organic matter, release energy, synthesize ATP for use in life activities, provide energy for various life activities of organisms, and provide raw materials for the synthesis of other compounds in the body.
Many common bacteria, actinomycetes and fungi are aerobic microorganisms.According to the characteristics of aerobic microorganism respiration, during the cultivation, try to make the culture directly contact or get more air. In production, vibration or aeration culture is often used. On the contrary, when maintaining goods, try to create an anoxic environment to limit the growth and reproduction of these microorganisms.[4]
