Introduction
Any living organism on this planet has to create energy in its body to perform any type of activity. Respiration is one of the activities that all living creatures must perform to exist. It can be photosynthesis or it can even be just walking from point A to point B.
As most of us know, the cell is the structural and functional unit of life, and each cell requires energy to function properly. As a result, cellular respiration refers to respiration that occurs at the smallest level of our bodies, namely the cellular level. The procedure guarantees that each cell does its job flawlessly. To create energy and respiration in the body of the organism, there is a particular mechanism that takes place. This mechanism is about breaking down glucose in the cells of the organism, which releases energy. To further elaborate on the process, glucose is just like a fuel that is necessary to create energy, and this is transferred in the form of electrons from molecules to cells.
Cellular respiration is again divided into two types, namely aerobic and anaerobic respiration. Let us understand how these two are similar yet different from each other. Though they both work on creating energy in the organism’s cells, the mechanism varies slightly, in terms of using a very important element in the process.
Aerobic Respiration Vs. Anaerobic Respiration
| Parameters | Aerobic Respiration | Anaerobic Respiration |
| Definition | Respiration process with the presence of Oxygen, while breaking carbon dioxide and water | Respiration process in the absence of Oxygen, while breaking glucose into lactic acid and carbon dioxide |
| Exchange of Gases | It takes place from inside the organism’s body, to the external environment | It takes place in the absence of the exchange of any gas |
| Place of Occurrence | The whole process occurs in mitochondria and cytoplasm | The mechanism only takes place in the cytoplasm |
| End Products | At the end of the respiration process with the existence of Oxygen, the end products are Carbon dioxide and H2O | With the absence of Oxygen, and using other elements for energy, the end products can vary from ethyl alcohol and carbon dioxide to energy |
| Organisms | Higher-body organisms use this respiration method to create energy. Like, mammals, plants, etc. | Yeast and bacteria usually tend to use this respiration method. Other than that, humans and other organisms use it at the time of heavy activities like running |
| Amount of Energy | With Glucose broken down in the process, this respiration produces around 18 times more energy than Anaerobic respiration | As there is less to no presence of glucose, the energy produced from anaerobic respiration is quite less than aerobic respiration. |
All cells require respiration to convert fuel into energy that may be used to power cellular operations. Adenosine triphosphate (ATP) is the result of respiration, and it utilises the energy stored in its phosphate bonds to power chemical processes. It is frequently referred to as the cell's "money."
What is Aerobic Respiration?
A type of cellular respiration which takes cells in the presence of oxygen, within the mitochondria of the cells in an organism’s body. And so it is a mechanism that typically breakdowns the glucose that is provided to our body through any type of intake, and converts it into carbon dioxide and water by giving out ATP (adenosine triphosphate). As we breathe, we intake oxygen-rich air and exhale carbon dioxide-rich air. As we breathe in, oxygen-rich air is carried to all regions of our bodies and, eventually, to each cell. With the aid of oxygen, the meal, which contains glucose, is broken down inside the cell into carbon dioxide and water. The act of breaking down food particles generates energy, which our bodies subsequently use. Aerobic respiration produces energy that enables plants, and animals, including humans, to develop and survive.
Our body mostly has aerobic respiration because it is more efficient than the other kind of respiration, because of the glucose. This is the reason why we breathe oxygen continuously, as we need to make each cell in our body get enough oxygen to have the mechanism of providing energy. And it is the same reason, why we exhale carbon dioxide. The end products of respiration are carbon dioxide, water and energy.
Glucose + Oxygen ----à Carbon dioxide + Water + Energy
Organisms that use oxygen to create energy, or in simple and straight words, any living thing that does aerobic respiration are called aerobes. Let us understand the types of aerobes around us.
- Obligate Aerobes: They must have free oxygen to survive. Obligate aerobes use oxygen for metabolism and break down sugar to create energy while performing cellular respiration. The final electron acceptor in the electron transport chain is oxygen. Fungi and bacteria, such as Mycobacterium TB, Bacillus, Nocardia asteroids, and Pseudomonas aeruginosa, are examples of obligate aerobes.
- Facultative Anaerobes: They produce energy by aerobic respiration in the presence of oxygen. In the lack of oxygen, they can, however, transition to the fermentation process. Bacteria such as Staphylococcus aureus, Escherichia coli, Salmonella, Listeria spp., and some eukaryotic species such as Saccharomyces cerevisiae are examples of facultative anaerobes.
- Microaerophiles: They require oxygen to survive, but in conditions with lower quantities of dioxygen than the atmosphere, i.e., 21% O2. Campylobacter and Helicobacter are two examples of microaerophiles.
Furthermore, there are various stages of aerobic respiration. As a result, Glycolysis, the Krebs cycle, and Oxidative phosphorylation are the three phases of Aerobic Respiration.
- Glycolysis: This is the first phase of the process. This process starts in the cytoplasm and is known as glycolysis, as we spell the stage of the process. Glucose is broken down into two molecules of pyruvate during this step, producing a little quantity of ATP and NADH.
- Krebs cycle: The citric acid cycle or the Krebs cycle is the second step of aerobic respiration that occurs in the mitochondria, where acetyl coenzyme A mixes with oxaloacetate to generate citrate. During this step, pyruvate is broken down further into carbon dioxide, producing additional ATP, NADH, and FADH2.
- Oxidative: The electron transport chain and oxidative phosphorylation are included in this step. At this step, the NADH and FADH2 formed in earlier stages transfer their electrons to a series of electron carriers, resulting in the production of a substantial amount of ATP via oxidative phosphorylation.
What is Anaerobic Respiration?
Anaerobic respiration screams "without air". This is a self-explanatory term saying how the process doesn't have oxygen in it, making it cellular respiration in the absence of oxygen. Anaerobic respiration is more commonly found in lower plants and microbes. In the absence of oxygen, glucose from meals is broken down into alcohol and carbon dioxide, resulting in energy generation. This indicates that organisms that utilise anaerobic respiration must eat more glucose than organisms that use aerobic respiration to generate the same amount of energy.
When you think about how and when this happens, we see times when our body needs energy while we are running and are short of air, it is then when our body uses partial glucose and produces energy along with the end product, lactic acid. And when you are continuously running, or doing any physical activities, your body muscles start to feel cramps, and the one to blame here is anaerobic respiration, as the accumulation of lactic acid causes these cramps in your muscles.
As anaerobic respiration can have various end products, based on how the mechanism takes place and what elements and chemicals it has, the flow can be of two types, with lactic acid or alcohol at the end of the metabolism.
Glucose à Lactic acid + Energy
Glucose àAlcohol + carbon dioxide + energy
Anaerobic respiration can take place in two different ways, namely, alcoholic fermentation and lactic acid fermentation. The elaboration of the same is given below.
- Alcoholic fermentation: A sort of anaerobic respiration mechanism that converts sugar molecules (glucose and other six-carbon sugars) to ethanol, releasing chemical energy in the form of ATP molecules. In the presence of the alcohol dehydrogenase enzyme, pyruvate generated by the glycolytic cycle is transformed into ethanol. This is why it is called "alcoholic fermentation."
- Lactic acid fermentation: It is a type of anaerobic respiration in which sugar molecules (glucose and other six-carbon sugars) are converted to lactate and chemical energy in the form of ATP molecules is released. The lactate dehydrogenase enzyme converts pyruvate generated after glycolysis to lactate during the fermentation process. It is also known as "Lacto-fermentation."
Difference Between Aerobic Respiration and Anaerobic Respiration in Points
The basic differences between these two types of cellular respiration mechanisms are:
- Oxygen is present in the process of Aerobic respiration and absent in anaerobic respiration.
- Though both respiration mechanisms take place inside the cell, they both differ from each other. As aerobic respiration can happen both in mitochondria or even in the cytoplasm, but anaerobic respiration happens only inside the cytoplasm of the cell.
- Oxygen and glucose are used to produce energy in aerobic respiration. Having no oxygen, glucose from any food intake is used to produce energy in anaerobic respiration.
- The amount of energy produced by each of the respiration mechanisms varies on a great level. Aerobic respiration is the higher range of energy providers.
- Along with energy, the end product of aerobic respiration is carbon dioxide and water. Whereas, in anaerobic respiration, it is lactic acid along with energy.
- Aerobic respiration takes a longer time when compared to anaerobic respiration.
- Plants and animals are common organisms that use aerobic respiration to produce energy on the day to day basis. Bacteria and yeast like lower-body organisms use anaerobic respiration for energy and also to survive or grow.
- Aerobic respiration produces almost 37 ATP per glucose and anaerobic respiration gives out only 2 ATP per glucose.
- The chemical flow for each respiration is
Aerobic: Glucose + Oxygen à Carbon dioxide + Water + Energy
Anaerobic: Glucose à Lactic acid + Energy
Conclusion
Cellular respiration is a complicated metabolic process that happens within cells to turn nutrients into ATP energy. The process is critical for all living species' existence since it supplies the energy needed for cellular functions such as growth, mobility, and the maintenance of cellular structures. While aerobic respiration is the most effective method of producing energy, anaerobic respiration can be advantageous in instances where oxygen is in short supply, such as during severe exercise when oxygen demand exceeds supply. During these periods, our muscles transition from aerobic to anaerobic respiration, allowing them to generate energy even in the absence of oxygen. Unfortunately, this causes lactic acid buildup, which can cause muscular tiredness and discomfort.
In this article, we learnt that the two basic forms of cellular respiration that supply energy to living cells are aerobic and anaerobic respiration. Aerobic respiration, which happens in the presence of oxygen, is the most prevalent kind of respiration in living creatures, whereas anaerobic respiration, which occurs in the absence of oxygen, is employed by certain species to create energy. While aerobic respiration is the most effective method of producing energy, anaerobic respiration can be advantageous in instances where oxygen is in short supply, such as during severe exercise.
The use of oxygen in the process of cellular respiration is the primary distinction between aerobic and anaerobic respiration. Aerobic respiration, as the name implies, is the mechanism by which cells generate the energy they require by consuming oxygen. This process generates carbon dioxide as a by-product, as well as ATP, the cell's energy currency. Anaerobic respiration is identical to aerobic respiration, except that it occurs in the absence of oxygen. As a result, lactic acid and ATP are produced as by-products of this process.
Contrary to common assumption, multicellular organisms, including humans, employ anaerobic respiration to generate energy, albeit this occurs only when the muscles do not receive sufficient oxygen as a result of particularly intense physical activity.
