The process of respiration generally involves a series of oxidation and reduction reactions. Some of the compounds get oxidized while others get reduced. What is the key factor that distinguishes the organisms into aerobic and anaerobic organisms? It is the compound that serves as an electron acceptor of the final reaction of respiration that distinguishes organisms. Organisms in which oxygen serves as a final electron acceptor are termed as aerobic organisms and the rest of them are termed as anaerobic organisms. All organisms use a variety of compounds such as glucose and amino acids during the process of respiration. Aerobic organisms such as animal and plant cells use oxygen as electron acceptor and donor. Anaerobic organisms such as bacteria and fungi use a variety of compounds such as sulfur, methane and hydrogen as electron acceptors and donors.
Large amounts of energy are generated during the process of respiration and it is harnessed in the form of ATP. It is the oxygen that is responsible for the synthesis of ATP. The process in which ATP is synthesized with the help of oxygen as a final electron acceptor is termed as oxidative phosphorylation. In addition to oxygen, the success of the process depends on the presence of a variety of enzymes especially the ATP synthase which catalyzes the formation of ATP from ADP and inorganic phosphate. Wondering where these ADP molecules are generated from? They are produced from the breakdown of compounds such as carbohydrates, proteins and fats that are the components of the food we take. These compounds are broken down in the processes termed as glycolysis and citric acid cycle.
What happens to the electrons that are taken by oxygen? They get combined with hydrogen resulting in the formation of water molecules. See how safely the electrons that are released into the body are eliminated? This process of elimination of accumulated electrons helps in the smooth running of electron transport chain, process in which the liberated electrons are accepted by oxygen and ATP is synthesized.
Aerobic respiration takes place in a great number of living things and serves as a means to eliminate carbon dioxide and other toxic materials from the body. It also helps to eliminate the free radicals that are responsible for a great number of health problems. All this life saving process of aerobic respiration takes place in the mitochondria, the subcellular structure present in all living cells. Hence, these mitochondria are termed as power houses of the cells. If the body cells of an aerobic organism are deprived of oxygen, then the organism dies within a very short period due to accumulation of toxic materials and lack of production of energy currency.
The major role of oxygen in aerobic respiration is to synthesize the energy currency of the cell ATP by accepting electrons generated from the breakdown of the macromolecules present in the food. It can also be said that oxygen is essential for the breakdown of the macromolecules present in the food we ingest.