The mitochondrion is a cell organelle responsible for production of energy. It is also known as the powerhouse of cell. The mitochondrion is a cell organelle characteristic to eukaryotic organisms. Its size ranges from 0.5 to 10 micrometers. A mitochondrion is composed of parts such as outer membrane, inner membrane, intermembrane space, matrix and mitochondrion-associated ER membrane. The outer and inner membrane of mitochondria are formed of proteins and phospholipid bilayers. The matrix of mitochondrion is formed of many different enzymes and it has many important functions.
Structure of Mitochondrial Matrix
A mitochondrion is formed of different parts and the matrix is one of them; it is enclosed inside the inner membrane of mitochondrion. The matrix of mitochondrion contains mainly soluble enzymes. The other components of this matrix are ribosomes and DNA. The contents of mitochondrial matrix are viscous in nature. This is unlike the cell cytoplasm that incorporates contents in a liquid state. Out of the total protein content of mitochondrion, 60-70% is present in the matrix.
The mitochondrial matrix houses hundreds of concentrated enzymes. Succinyl coenzyme A synthetase is one of the many enzymes present in mitochondrial matrix. This enzyme acts as a catalyst in the process of converting succinyl-CoA to succinate.
One of the important functions carried out by enzymes in the matrix is that of oxidation of fats and carbohydrates in Krebs cycle. The function of mitochondrial matrix is that, it acts as a site for important reactions and processes that produce energy for cells. It is the site for Krebs cycle and ATP synthesis. A short explanation of ATP synthesis and Krebs cycle is presented below. The details about electron transport chain (an intermediate process) should also prove to be useful in understanding the two processes.
Site for Krebs Cycle
It is also referred to as citric acid cycle and holds great importance from the point of oxidation of carbohydrates and fats. This oxidation of fats and carbohydrates generates energy required for the functioning of body. The mitochondrial matrix is the site where the citric acid cycle takes place. Oxygen is used as a raw material for this process.
Electron Transport Chain
The transfer of electrons down the electron transport chain is responsible for energy production. The inner membrane of mitochondrion is the site of this chain. The electron transport chain (ETC) transfers electrons from Nicotinamide adenine dinucleotide (NADH) to oxygen. The process of electron transport across inner membrane of mitochondrion results into an electrochemical proton gradient. This proton gradient is responsible for synthesis of ATP. The process of ATP synthesis is explained in the next paragraph.
Synthesis of ATP (adenosine triphosphate) is an important mitochondrial function. The products obtained from Krebs cycle, amino acid oxidation and fatty acid oxidation are used in the synthesis of ATP. The proton gradient created by the electron transport chain drives the process of ATP formation in the mitochondrial matrix.
Site for Urea Cycle
It is the chemical reaction in which urea i.e. ((NH2)2CO) is generated from NH3 i.e. ammonia. This process of urea cycle takes place in 5 steps. Out of the total 5 steps, 3 take place in mitochondrial matrix.
The mitochondrion is one of the most important cell organelle, owing to its functionality of production of energy. Without the mitochondrion and its matrix, it is not possible to support the functions of our body. All the enzymes and other elements of mitochondrial matrix described above are necessary for the smooth functioning of the processes of this cell organelle.