What is cellular respiration?
The biochemical process of oxidation of food that occurs within the living cells for releasing the energy which is stored in it as food is called cellular respiration. The other name of this is biological or cellular oxidation. See viral biochemical pathways involved by it which is collectively referred to as respiratory metabolism. Oxidation of food occurs very slowly in a stepwise and contour manner under the influence of enzymes so that the reactions take place at a lower temperature in this process. In difference to this, chemical oxidation or burning is a very rapid process and it happen at a much higher temperature because the heat generation is much in this process.
The purpose of cellular respiration or biological oxidation to release the energy throat in the boot quite slowly so that part of it is captured in ATP and the remaining is liberated as heat. As the heat is generated by many steps and not all at a time, body temperature is maintained in its normal level.
Cellular respiration involves reactions which give up energy wherein the less stable organic materials containing more energy are decomposed to more stable end products that contain less energy. The energy rich Carbone bonds of the food molecules supplies the energy released in respiration. The hydrocarbon groups are energy rich and hence least stable virus carbon dioxide is an anhydride or hydrogen free compound and hence it is most stable. There are three processes interrelated with each other which comprises the cellular respiration. Those three processes are:
1) Hydrogen transfer.
2) Food decomposition.
3) Energy transfer.
Respiratory sub substrate: -
in the process of cellular respiration the food materials stored in the protoplasm which are oxidised pod liberation of energy are called fuels of the cell or respirator substrate. As carbohydrate, protein and fat are used as respiratory substrates those are called energy yielding foods. The Chief fuel is glucose as it is the most easily available as well as utilisable food for majority of the cells. But fat and protein may also be utilised in respiration. Fats and proteins are either converted to glucose or to a compound which is an in-between product of glucose and then enter into the pathway of oxidation of glucose. In some of the cells organic acid may also used as the substance of respiration.
Normally only carbohydrates are oxidised and this type of respiration is called floating respiration. When carbohydrates and fats are completely used for respiration and there is an acute shortage of fuel in the cell the Proteins of protoplasm work as the respiratory substrate and this is called protoplasmic respiration. So they are may be some wasting of protoplasm when protein is used as the respiratory substrate. So we can say that on the basis of substrate used, the cellular respiration may be divided into two types: those are floating respiration and protoplasmic respiration.
Aerobic and Anaerobic Respiration
On the other hand depending upon the nature of oxidation of substrate the cellular respiration may be divided into two types: those are (1) Aerobic respiration and (2) Anaerobic respiration.
(1) Aerobic respiration: – in Arabic respiration, molecular or he oxygen participates in the oxidative process. In this case the food substrate is completely oxidised, liberating carbon dioxide and water as the end products and a large amount of energy is removed. The organisms which cannot survive without oxygen are called aerobes.
(2) Anaerobic respiration: – when the oxidation is carried out without participation of free oxygen the process is called anaerobic respiration. In this case the food is incompletely oxidised so that the end products are ethyl alcohol, lactic acid etc. and the liberated amount of energy are quite small. The organisms which can go on anaerobic respiration are called anaerobes. Anaerobes may be of two types, those are: –
I) Facultative anaerobes: The organisms that can live both in presents and in absence of oxygen are called facultative anaerobes or partial anaerobes.
II) Obligate anaerobes: those organism which survive only in oxygen free environment and are died in presence of oxygen, that is they can respire only as anaerobic are called complete anaerobes or obligate anaerobes.