Mitochondria are present in all eukaryotic cells and are the major sites of aerobic respiration within cells. they were first seen as granules in muscle cells in 1850. The number of mitochondria per cell varies considerably and depends on the type of organism and the nature of the cell. This article gives the information on Structure and function of mitochondria?
- 1850 – Kolliker – observed in muscle cells of insects
- 1882 – Flemming– gave the name as “filia”
- 1892 – Altmann– gave systematic name observation name as “Bioblast”
- 1897-98 – Benda– gave a name as “Mitochondria”. He stained the mitochondria with “alizarin” and “crystal violet”.
- 1900 – Michaelis– stained mitochondria with “Janus green”
- 1934 – Bensley & Hoperr – said mitochondria is the site for the cellular respiration.
- 1940- Palade and Sjostrand – They worked out the fine structure of mitochondria under the electron microscope.
- Fuchsinophilic granules,
- Parabasal bodies,
Structure and function of mitochondria
Biochemistry and Anatomy of Mitochondria
Mitochondria (Mc) were first observed by “Altmann” in 1894 who described as “bioblasts”. Benda (1897) called them “mitochondria”. (mitoG =thread; chondrionG=granule). Here are the Structure and function of mitochondria.
- The number of Mc varies with the cell type and functional stages. In eukaryotes, approximately 2000 Mc copies one-fifth of its total cell volume.
- The Mitochondria’s chemical composition is concerned, It consists of 65-70% proteins, 25-30% lipids, 5-7% mitochondrial DNA and 0.5%RNA. The outer membrane of the mitochondria has “porins”, which permits molecules up to 10kd.
- Mitochondrial Matrix is gel like a solution, containing the high concentration of soluble enzymes, substrate, nucleotide cofactors, ions.
- The Mc is a subcellular organelle having the outer and inner membranes enclosing the matrix.
- The inner membrane is highly selective in its permeable characteristics.
- The inner membrane contains the respiratory chain and translocation systems.
- The knobs like protrusions represent the ATP synthase system.
- The inner membrane is folded into a series of internal ridges called “Cristae”, which may be longitudinally or transversely oriented, branched or tabular.
Hence, there are two compartments in Mitochondria: the intermembrane space between the outer and inner membranes and the matrix, which is bounded by the inner membrane. Most of the reactions of the TCA cycle (citric acid cycle ) and fatty acid oxidation occur in the matrix.
Enzymes localization in Mitochondria
LOCALISATION OF SOME ENZYMES IN RAT-LIVER MITOCHONDRIA
Chemical Composition of Mitochondria
- The major constituent of mitochondria is proteins (4/5) and liquids (1/5).
- The lipid content is composed of 90 per cent phospholipids (Lecithin and Cepahlin), about 5 per cent free fatty acids and triacylglycerides.
- Mitochondria are rich in enzymes related to substrate oxidation, respiration, energy conservation, oxidative phosphorylation and Kreb’s cycle.
- A heterogeneous group of enzymes related to phospholipid metabolism and fatty acid oxidation are present in the outer compartment and outer membrane.
- Cu++, Mg++, HPO4-, Cl-, RNA and DNA (without histone, a protein) is also reported to occur.
What are the functions For Mitochondria? The Mitochondria play an important role in Cellular Respiration.
- The Mitochondria are organelles which transfer the chemical energy of the metabolites of the cell (through Krebs cycle and the respiratory chain) into the high-energy phosphate bond of ATP (production of ATP).
- Thus, mitochondria are the “power house of the cell”, that produce the energy necessary for many vital cellular functions via, motility contraction (muscle contraction), biosynthesis of cell bioluminescence etc.
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