Every living thing requires energy to stay alive. There are many physiological processes some voluntary and some conscious that all of the living beings encounter and experience and all of them require some amount of energy to perform those activities. However, that energy cannot be supplied from outside the body. The body has to generate the energy all by itself. Now this energy is used in different activities and bodily tasks among which, the mammals and the birds, require most of the energy in maintaining their body temperature.
But there are many other tasks too that the body performs and requires the energy to perform them and they are cell division, working the muscles, synthesizing the proteins and allowing the chemicals to react, helping the nerves to carry the messages to the brain and so on. This energy that the body requires is produced by a complex procedure called respiration. In simple terms, it is the breaking down of the glucose that the body takes in, into energy. And this process is done by almost every living cell, without stopping, all the time.
Types of respiration:
Living things must respire all the time. The moment they stop respiring is the moment they will stop living. But this process of respiration is an intense and a complex one. It is done through two different procedures and they are the aerobic and the anaerobic respiration. The difference between aerobic and the anaerobic respiration is that the former uses oxygen in releasing the energy and the latter doesn’t.
The process that involves in the release of energy is more complex in the aerobic respiration cycle. There are quite some steps and series of chemical reactions after which the energy is generated. The aerobic type of respiration is a form or kind of cellular respiration that need and involves oxygen for generating the energy from glucose. This glucose is available from the nutrients that the body takes in from the food. On the contrary, the anaerobic respiration does not require oxygen to release or generate energy and hence, it is called anaerobic; literally meaning ‘without air’.
When the difference between aerobic and the anaerobic respiration is considered, there are quite many. In the aerobic process, the oxygen is the electron acceptor or the generator of energy, whereas in the anaerobic process, there is no oxygen required to release the energy. In almost every cell the aerobic respiration takes place but the anaerobic process takes place mostly in prokaryotes. The amount of energy that is released in presence of air or oxygen is higher than the amount released in the absence of oxygen.
Process of aerobic respiration:
The term aerobic respiration comes from the word “air” as it involves oxygen in the process of generating energy. In the presence of air, rather oxygen as well as some other organic substrate, the glucose releases the energy. The entire process of aerobic respiration takes place in three different stages and they are Glycolysis, Krebs cycle and electron transport chain. The very first step of energy generation, from the glucose that is consumed, in presence of air is known as Glycolysis. Literally it means ‘splitting up of sugar’.
If you are looking for the aerobic respiration equation, you must at first know how the Glycolysis process is done. In this process, a single glucose molecule is split up into 2 molecules of pyruvic acid, 2 molecules of NADH, 2 molecules of ATP and 2 molecules of water. The Glycolysis procedure takes place in the cytosol of the cell. This process then follows the Krebs Cycle. This is the final oxidation reaction that follows the electron transport chain. Once this cycle is complete, the majority of the ATP or the adenosine triphosphate is released. The Krebs cycle is also known as the citric acid cycle. This is the process that takes place in the mitochondria of the living cells. When the process starts, it begins with the breaking or splitting up of two pyruvates molecules into two acetyl-coenzyme A (acetyl-CoA), two NADH and two carbon dioxide molecules. The formation of the acetyl-CoA is very important as this is the product that creates a link between the previous process of Glycolysis and the present Krebs cycle.
The process of aerobic respiration that then follows in the Krebs cycle, comprises of eight steps and the final products are carbon dioxide and ATP molecules and a few very important coenzymes. The carbon dioxide that is created in this reaction is exhaled through breathing out. The reason why this process is called a cycle is that it finally produces a product namely oxaloacetate, which then helps back in the formation of the acetyl-CoA. As this acetyl-CoA would be again starting this citric acid process, it is known as the Krebs cycle.
The respiration equation equation:
The entire process can be summed up in one single equation in which the initial products of glucose that is consumed and the oxygen that is breathed in, react together through the steps called Glycolysis and Krebs Cycle to produce carbon dioxide, water and energy. The carbon dioxide is exhaled out and the energy is stored in the form of ATP for the body to use later. The simple equation goes like this –
C6H12O6 + 6O2 → 6CO2 + 6H2O + 2900 kJ/mol
Apart from the water and the carbon dioxide that are produced as the by-products of the reaction, there are many other coenzymes also produced. However, the most important aspect of this aerobic respiration equation is that with the oxidation of one molecule of glucose, 2900 kJ/mol energy is released. This energy is stored in a special form called ATP or the Adenosine triphosphate. This helps the body to reuse the energy whenever required.
The entire process of aerobic respiration takes place both in the plants as well as animal cells. However, in case of plants, the oxygen enters their body through stomata and the energy is released in the process of respiration followed by photosynthesis.