Steps Of Cellular Respiration

Cellular respiration is the process of mixing oxygen with food molecules through cells. In this procedure, the chemical energy from the food substances converts into usable energy due to which we perform daily activities. Waste is also released in the form of water and carbon dioxide during the entire process. This is a type of aerobic respiration, as it takes place in the presence of oxygen. Organisms that depend on anaerobic respiration convert chemical energy through fermentation. Cellular respiration occurs in all organisms that rely on oxygen for sustaining their life. 

Cellular Respiration 

Cellular respiration is the biological procedure in which the chemical energy of ingested food components changes into biological energy. The waste of food components is converted into water, which comes out in the form of sweat and urine. 

Steps of cellular respiration 

The whole process of cellular respiration is divided into three steps. These steps are:

• Glycolysis 
• TCA cycle (Tricarboxylic acid cycle) 
• Respiratory-chain phosphorylation (oxidative phosphorylation) 

Glycolysis

Glycolysis is also called the Embden-Meyerhof-Parnas pathway and glycolytic pathway. It is a major step of cellular respiration. Ten chemical reactions break down glucose molecules into two types of pyruvate molecules of pyruvic acid. In this stage of cellular respiration, the glucose of organic nutrients like proteins, fats, and carbohydrates is changed into energy. The converted energy is stored in Adenosine triphosphate (ATP). Another chemical compound named Nicotinamide also breaks in this step, and this compound changes into NADH. All these substances are converted into Pyruvate molecules, which go into the mitochondria. After reaching the mitochondria, Pyruvate molecules are converted into Acetyl-coenzymes. This conversion of Pyruvate molecules into Acetyl coenzymes is called Pyruvate oxidation and transition reaction of cellular respiration. 

TCA cycle (Tricarboxylic acid cycle) 

TCA cycle stands for Tricarboxylic acid cycle. The TCA cycle is also known as a citric acid cycle or Krebs. It is a major step in cellular respiration which breaks down the organic fuel molecules into simple molecules. The TCA cycle consists of eight chemical reactions in which eight different enzymes play different roles at different levels. The energy obtained after converting the organic fuel molecules is stored in the Flavin adenine dinucleotide and NAD+ compounds. Then, this stored energy is changed into Adenosine triphosphate. Halfway through this procedure, the organic fuel molecules are converted into three NAD+ molecules, which are formed after adding Hydrogen ions in the same number of Nicotinamide adenine dinucleotides. One Flavin adenine dinucleotide molecule is formed, which is later reduced by adding Hydrogen ions and is converted into FADH2. In the next half-cycle, the carbon dioxide produced as a waste product is released out of the body. This next stage is called Oxidative phosphorylation. 

Oxidative phosphorylation

Oxidative phosphorylation is the last step of cellular respiration. In this stage, the Hydrogen atom gets removed from the pair of Nicotinamide adenine dinucleotide and Flavin adenine dinucleotide. In simpler terms, the oxidation of organic molecules takes place in this stage, and the released hydrogen ions get combined to form a molecule of hydrogen. The hemoproteins, which contain iron, release one atom of the oxygen molecule. The released oxygen molecules get combined with the hydrogen molecules and get converted into water. The flow of oxygen molecules or hydrogen molecules in this stage is called the electron transport chain. This formed water is a waste product released from the body in the form of sweat or urine. When the hydrogen molecule or pair of hydrogen ions combines with oxygen, it generates three molecules of Adenosine triphosphate. 

Oxidative phosphorylation is a significant stage of cellular respiration in which lots of energy from food molecules get stored and is sent to the cell for consumption. Along with this, the released waste (carbon dioxide and water) gets removed outside the body. While we exhale the air, carbon dioxide gets water removed through urine and sweat. 

The Process of Cellular Respiration in Mitochondria

The degradation of food molecules takes place in mitochondria. In this process, the energy of chemical compounds is converted into energy-rich compounds. The Adenosine triphosphate of mitochondria stores the broken chemical energy of food molecules and then releases it in the further stages of cellular respiration. After that, the enzymes at different stages work on the chemical energy to convert it into useful energy. 

Conclusion 

Cellular respiration is a systematic biological procedure in which the chemical energy gets changed into useful energy, and the inhaled oxygen gets converted into carbon dioxide. The body consumes this energy through cells. The cells of our body release this energy into the bloodstream, and when it reaches the several organs of our body, it facilitates their functioning. It is a continuous procedure, which goes on even if we are sleeping. It occurs fast when we indulge ourselves in heavy physical work and occurs at a slow rate when sleeping or resting.