Anaerobic Respiration- Definition, Types, Steps, Equation, Products, Uses


Respiration is a vital process for all living cells, as it provides them with the energy they need to perform various functions. Respiration involves the breakdown of organic molecules, such as glucose, and the transfer of electrons to an electron acceptor. The most common type of respiration is aerobic respiration, which uses oxygen as the final electron acceptor and produces carbon dioxide and water as waste products. Aerobic respiration is very efficient and can generate up to 38 molecules of ATP (adenosine triphosphate), the universal energy currency of cells, from one molecule of glucose.

However, not all cells can perform aerobic respiration, either because they lack the necessary organelles (such as mitochondria) or because they live in environments where oxygen is scarce or absent. In such cases, cells can resort to anaerobic respiration, which is a type of respiration that does not require oxygen. Anaerobic respiration uses other substances, such as nitrate, sulfate, sulfur, or organic compounds, as the final electron acceptors and produces different waste products, such as lactic acid, ethanol, methane, hydrogen sulfide, or nitrogen gas. Anaerobic respiration is less efficient than aerobic respiration and can generate only 2 molecules of ATP from one molecule of glucose.

Anaerobic respiration can be divided into two main types: fermentation and anaerobic cellular respiration. Fermentation is a simple process that occurs in the cytoplasm of cells and does not involve an electron transport chain. Fermentation converts pyruvate, the end product of glycolysis (the first stage of both aerobic and anaerobic respiration), into either lactic acid or ethanol, depending on the type of organism and the enzymes involved. Fermentation regenerates NAD+, which is needed for glycolysis to continue. Fermentation is common in bacteria, fungi (such as yeast), and some animal cells (such as muscle cells).

Anaerobic cellular respiration is a more complex process that occurs in some prokaryotic cells and involves an electron transport chain. Anaerobic cellular respiration transfers electrons from NADH and FADH2 (the reduced coenzymes produced during glycolysis and other metabolic pathways) to various electron acceptors other than oxygen. The electron transport chain creates a proton gradient across a membrane, which drives the synthesis of ATP by ATP synthase. Anaerobic cellular respiration is important for many ecological processes, such as biogeochemical cycles, sewage treatment, bioremediation, and biogas production.

In this article, we will explore the definition, types, steps, equation, products, and uses of anaerobic respiration in more detail. We will also compare and contrast anaerobic respiration with aerobic respiration and fermentation. By the end of this article, you will have a better understanding of how different organisms obtain energy in different ways depending on their environment and evolutionary history.