Aerobic Respiration Stages: Step by Step

Respiration is one of the vital process related to chemicals that is carried by all the living beings staring from plants to humans to get the energy released for life.

Aerobic respiration is concerned with reactions that are controlled by enzymes. The energy that is released by this reaction has lipids and carbohydrates and the aerobic respiration stages have four phases called to be-

Aerobic respiration is the type of cell to cell respiration that is seem in the area having the space for oxygen gas that is needed to make energy for the food. This type of respiration is general in most of the animals, humans, birds, plants and also the rest mammals. Here the end products that are made are said to be carbon dioxide and water.

Cellular reactions are a set of the metabolic actions and methods that are seen in the cells of the organism to have the chemical energy converted from the part of oxygen molecules or the nutrients to adenosine triphosphate with leaving behind waste materials. Mostly the reactions they include are catalytic that break up large molecules.

The breakage of bonds to smaller portion is done by getting the weak bonds to break and in most cases the oxygen molecules are the replaced by many bonds that are stronger in the products. Respiration is said to be one of the key to help the cell release its energy to get the cell activity fuel. The overall reaction takes place in a chain of biochemical steps.

aerobic respiration stages
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Aerobic respirationWikipedia

The aerobic reparation stages need the oxygen to make ATP. Though the fats, carbohydrates, proteins are taken in as reactants, this is the preferred sign to have glycolysis to breakdown and need pyruvate to mitochondria

in order to fully oxidized. Carbon dioxide and water are the products that are the outcome of this and end by breaks ADP bond.

Aerobic respiration formula

Aerobic respiration is a biological process where glucose is treated as a food and then is transferred to energy in the presence of having oxygen.

There are many stages in aerobic respiration stages and the chemical formula is Glucose (C6H12O6) + Oxygen 6(O2) → Carbon-dioxide 6(CO2) + Water 6 (H2O) + Energy (ATP). It has ΔG = −2880 kJ per mol of C6H12O6.

The negative sign means that the reaction can take place spontaneously. According to the reaction given, the energy is said to be released by having the molecules of glucose splitting up with the use of gas oxygen. At the final phase of the reaction the end products that is made are finally the energy, carbon dioxide and water.

There is an energy of about 2900Kj that is released at the time of getting the glucose broken and in turn to this the energy is used up to make ATP. ATP is adenosine triphosphate and its molecules are the one that is used by the system for several motifs. The worth it FADH2 and NADH is transferred to more ATP via an electron chain transport along with proton and oxygen acting as terminal acceptors of electron. Respiration is used by all cells to turn fuel into energy that can be used to power cellular processes

The method of aerobic respiration stages along with the accrual process takes place in almost all the multicellular organism that consists of plants the humans, animals and the rest creatures. At the time of respiration in plants, the oxygen is supposed to enter the cells via stomata and then the green plants get to synthesize the food. A chemical process in which oxygen is used to make energy from carbohydrates (sugars). Also called aerobic metabolism, cell respiration, and oxidative metabolism.

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Aerobic respiration stages

The completion of the aerobic respiration takes place in four steps as mentioned before-


It is the common phase for the aerobic respiration stages and then the method of glycolysis is seen inside the cytosol of cell.

At the time of glycolysis method, the molecules of glucose are spitted and then separated into ATP and is two in number along with two NADH that are later used in the method of aerobic respiration.

It can be said to be a translation for sugar splitting and takes place with or even without the use of oxygen. In the situation of aerobic respiration, the methods get converted to one single glucose particle and then gets converted to the molecules of pyruvate that makes up energy in the form of molecules of ATP of two. There are four of the ATP molecules of pyruvic acid that makes energy consumption a part.

Glycolysis - Wikipedia
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The general and initial phase of glucose is generated to have the reactivity increased and make a balance in decrease order to have the molecules be cleaved in the two pyruvate particles by the enzyme called aldolase. During the phase of glycolysis, there are four molecules of ATP, and the two of NADH are made when the pyruvate is oxidized. It starts with glucose and then glycogen gets converted.

The basic conversion of having the reaction of enzymes getting catalyzed and then having it converted into the two of the molecules of the lactate in the absence of oxygen and making two atoms of pyruvate with having oxygen is glycolysis. In absence of the gas oxygen it is called to be anaerobic glycolysis that is performed while there is a shortage of oxygen found.  

Link Reaction

They very first step in the aerobic respiration stages is the link reaction that helps the transport of pyruvate in the mitochondria.

This type of respiration makes the use of the oxygen that is available for future use and then oxides the molecule of sugar for more yield of the adenosine triphosphate. ATP is generated by substrate-level phosphorylation by high-energy compounds.

The name of link reaction is given as it connects the products of the process of glycolysis with the process of aerobic respiration inside the mitochondria. All these are seen within the cytoplasm of the cell or the power house of cell being the mitochondria. There is the space of cytosol that is involved and the mitochondrial matrix.

Adenosine triphosphate - Wikipedia
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Glycolysis is a cytoplasmic pathway which breaks down glucose into two three-carbon compounds and generates energy. Glucose is trapped by phosphorylation, with the help of the enzyme hexokinase. Adenosine triphosphate (ATP) is used in this reaction and the product, glucose-6-P, inhibits hexokinase. Glycolysis takes place in 10 steps, five of which are in the preparatory phase and five are in the pay-off phase.

Pyruvate is said to be transported from the matrix of mitochondria and is only one in number and is done by the carrier proteins seen on the membrane of the power house.  The pyruvate is then seen to lose an atom of carbon that makes the molecule of carbon dioxide. Then there is seen the making of the two carbon formula that help form the group for acetyl.

The formation of the acetyl group is done when their oxidases is a loss of an atom of hydrogen atoms that gets to oxidase and then helps in having the NAD reduced to NADH and hydrogen atom. The combination of acetyl set compound gets to combine with the coenzyme A that helps in the making of acetyl coenzyme A also called as acetyl CoA.

As there is a splitting of the molecules of glucose into two of the molecules of pyruvates it helps in the linkage of the reaction that takes place in the molecule of glucose twice. The method of link reaction process with each of the molecule of glucose gets to produce link reaction acetyl. It can be represented in simple terms by CoA (×2), NADH + H+ (×2) and CO2 (×2).

Krebs cycle

It is known to be the tricarboxylic acid cycle and also citric acid cycle and is also the source of supplying energy and is important for this respiration.

The cycle gets to harness the chemical energy that is seen to be available of the acetyl coenzyme A into getting it reduced the power of nicotinamide adenine dinucleotide which is called the NADH.

This cycle is said to be portion of a great metabolism of glucose where the glucose tends to get oxidized to make the pyruvate that is after this again oxidized and then enters the TCA cycle with the name given to be acetyl-CoA. The pathway to these compounds are given to lead to the vital compounds like the amino acids, fatty acids and porphyrins. It is one of the most important reaction sequences in biochemistry. 

The start of the acetyl cycle is given by the name of acetyl CoA. It starts with the making of an enzyme of aldol addition and reaction of acetyl CoA to oxaloacetate that makes citrate. The making of the citrate if then isomerized by getting the chain dehydrated and then again hydrated to yield 2R, 3S- isocitrate. It is the series of reactions responsible for most of the energy needs in complex organisms, the molecules that are produced in these reactions can be used as building blocks for a large number of important processes.

Citric acid cycle - Wikipedia
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After this there is an oxidation of the enzymes and then there is a decarboxylation that leads to the outcome of 2-ketoglutarate. The process is further analyzed by getting the 2-ketoglutarate converted to the succinyl–CoA. The metabolite is then hydrolyzed to succinate and is then coupled to the phosphorylation of GP to GTP.

There is denaturation seen for the enzymes by the Flavin adenine dinucleotide which is dependent on succinate dehydrogenase that yields fumarate. There is a method of stereospecific hydration that is seen and after this process of stereospecific hydration the fumarate is catalyzed by the enzyme fumarase and is converted to L-malate. This is the second last step concerned. The Krebs cycle continuously recycles, reusing the substrates and enzymes with an overall reaction given by a reaction.

The last step consists of the NAD- that is couple for oxidation of the L-malate to the oxaloacetate and is then catalyzed by the malate dehydrogenase and then this is termed to be the end of the Krebs cycle also called as TCA or the Citric acid cycle. Before the start of this cycle, the glucose is first converted to acetyl-CoA and yield 2 of its molecule. Thus the cycle turns twice yielding GRTP, FADH2 and 3 NADH. The reaction begins with the joining of acetyl-coenzyme A with oxaloacetate and water to form citrate.

Oxidative phosphorylation

It is the process where the energy gets harnessed via the series of the protein complex that is embedded inside the inner mitochondria membrane.

It is also called to be the electron transport chain linked with phosphorylation or the end metabolites oxidation oath where the cells are sued to oxidase the nutrients with having to release the chemical energy to make ATP.

In the eukaryotes they take place inside the mitochondria. All the organism that are aerobic carry out the process of oxidative phosphorylation. This is a vital step for aerobic respiration stages and is indeed the last one on the go. This path is said to be pervasive as it tends to give out more energy than the fermentation one. This generates potential energy in the form of a pH gradient and an electrical potential across this membrane.

In eukaryotes, these redox reactions are catalyzed by a series of protein complexes within the inner membrane of the cell’s mitochondria, whereas, in prokaryotes, these proteins are located in the cell’s outer membrane. These linked sets of proteins are called the electron transport chain. In eukaryotes, five main protein complexes are involved, whereas in prokaryotes many different enzymes are present, using a variety of electron donors and acceptors.

The energy is harvested in the bonds of the glucose ad is released by the cells in the Krebs cycle or the TCA cycle that makes carbon dioxide and have the electrons donated. The method of oxidative phosphorylation uses these molecules and also oxygen to make ATP hat is seen all the way of the cell and needs energy. The energy transferred by electrons flowing through this electron transport chain is used to transport protons across the inner mitochondrial membrane, in a process called electron transport.


I am Ankita Chattopadhyay from Kharagpur. I have completed my B. Tech in Biotechnology from Amity University Kolkata. I am a Subject Matter Expert in Biotechnology. I have been keen in writing articles and also interested in Literature with having my writing published in a Biotech website and a book respectively. Along with these, I am also a Hodophile, a Cinephile and a foodie.

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