Climate Change 5: Evolution 1. Evolution Evidence 2. Natural Selection 3. Classification 4. Cladistics 6: Human Physiology 1. Digestion 2. The Blood System 3. Disease Defences 4. Gas Exchange 5. Homeostasis Higher Level 7: Nucleic Acids 1. DNA Structure 2. Transcription 3. Translation 8: Metabolism 1. Metabolism 2. Cell Respiration 3. Photosynthesis 9: Plant Biology 1. Xylem Transport 2.
Phloem Transport 3. The electron transport chain, where the majority of ATP is formed, requires a large input of oxygen. However, many organisms have developed strategies to carry out metabolism without oxygen, or can switch from aerobic to anaerobic cell respiration when oxygen is scarce.
During cellular respiration, some living systems use an organic molecule as the final electron acceptor. In contrast, some living systems use an inorganic molecule as a final electron acceptor. Both methods are called anaerobic cellular respiration, where organisms convert energy for their use in the absence of oxygen.
Certain prokaryotes, including some species of bacteria and archaea, use anaerobic respiration. For example, the group of archaea called methanogens reduces carbon dioxide to methane to oxidize NADH. These microorganisms are found in soil and in the digestive tracts of ruminants, such as cows and sheep. Eukaryotes can also undergo anaerobic respiration. Some examples include alcohol fermentation in yeast and lactic acid fermentation in mammals.
The fermentation method used by animals and certain bacteria like those in yogurt is called lactic acid fermentation. This type of fermentation is used routinely in mammalian red blood cells and in skeletal muscle that has an insufficient oxygen supply to allow aerobic respiration to continue that is, in muscles used to the point of fatigue. The excess amount of lactate in those muscles is what causes the burning sensation in your legs while running.
This pain is a signal to rest the overworked muscles so they can recover. In these muscles, lactic acid accumulation must be removed by the blood circulation and the lactate brought to the liver for further metabolism.
The chemical reactions of lactic acid fermentation are the following:. The enzyme used in this reaction is lactate dehydrogenase LDH. The reaction can proceed in either direction, but the reaction from left to right is inhibited by acidic conditions. Such lactic acid accumulation was once believed to cause muscle stiffness, fatigue, and soreness, although more recent research disputes this hypothesis.
Anaerobic respiration can be found only in the cytoplasm of a cell. The end products of anaerobic respiration vary, such as gases, alcohols, acids, and energy. In fermentation, only 2 ATPs are produced. Also, there is incomplete oxidation of carbohydrates.
It occurs in simple prokaryotes, yeasts, and the muscle cells of humans during intense exercise. Anaerobic respiration is shorter than aerobic respiration. To summarize what has been described so far, here are the equations of various cellular respirations:. All living organisms undergo cellular respiration. In certain types of bacteria and yeast, anaerobic respiration is preferred.
It gives them the advantage of surviving or thriving in an anoxic environment that would be lethal to aerobic organisms. Anaerobic respiration also has a very high speed. It produces ATP very rapidly. Aerobic respiration, on the other hand, produces ATP rather slowly. One of the most significant functions of fermentation is that it protects the cells from dying in the small amount of time between each breath and during intense activity when the red blood cells fail to provide adequate oxygen to the body cells due to under-oxygenation.
Fermentation takes over as this happens and releases a substance called lactic acid which keeps the cells of the body intact during the above-mentioned cycles of under-oxygenation. Although this quite useful for the time being, yet unfortunately, a build-up of lactic acid may cause discomfort in the muscles later. Lactic acid production in muscles. During vigorous exercise, our muscles use oxygen to generate more ATP as compared to the supply.
When this happens, the muscle cells undergo glycolysis faster than they can supply oxygen to the mitochondrial electron transport chain. As a result, anaerobic respiration and lactic acid fermentation occur within the cells and during extended activity, the built-up lactic acid will keep our muscles painful. Alcoholic fermentation by yeasts.
Fermentation is another category of anaerobic respiration that occurs in anaerobic organisms such as yeast. When carbohydrate-rich substances are bottled with yeasts to ensure a minimal oxygen level in the container, yeasts undergo the process of anaerobic respiration.
As a process, fermentation occurs where the yeast converts sugars into ethyl alcohol. Methanogens are prokaryotes that belong to the Archaea. These species are considered methanogens because they produce methane as a by-product by oxidizing carbohydrates in the absence of oxygen.
This process is called methanogenesis. It is also a type of fermentation that results in the production of methanol, specific alcohol. This process is also referred to as methanol poisoning.
Methanol poisoning can lead to nerve injury or even death in some cases. Propionic acid fermentation occurs when certain bacteria use carbohydrates such as lactose and glucose to create propionic acid and carbon dioxide. In Swiss cheese, the most common use of this method can be observed.
During this process, the carbon dioxide gas produced results in the formation of bubbles in the cheese along with the distinct flavor due to carboxylic acid. Try to answer the quiz below and find out what you have learned so far about anaerobic respiration. Plants are responsible for incredible feats of molecular transformation. Plant processes, such as photosynthesis, photophosphorylation, chemiosmosis, carbon fixing reactions, respiration, are presented in this tutorial Read More.
Cell respiration is the process of creating ATP. It is "respiration" because it utilizes oxygen. Know the different stages of cell respiration in this tutorial This tutorial deals with the structure and function of flowers, fruits, and seeds. Also included here are the types of fruits, fruit dispersal mechanisms, and seed germination. The distinctions between dicots and monocots, the two major groups of flowering plants, are presented in this tutorial Skip to content Main Navigation Search.
Dictionary Articles Tutorials Biology Forum. Table of Contents. Question: What happens during anaerobic cellular respiration? Question: What does anaerobic respiration produce? In fermentation, lactic acid or ethanol and molecules of ATP are the end products. Quiz Choose the best answer.
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