Mitochondria

The mitochondria are visible under a light microscope and their detailed structure has been revealed under electron microscope.

(I). Introduction and discovery

Mitochondria are one of the most important cell organelles found in all eukaryotic cells. They are lacking in certain unusual anaerobic protozoans. They are absent in mature RBC , but they are present before the RBC mature.
Mitochondria were first discovered by Kolliker in the year 1880.
The term “Mitochondria” was given by Benda in 1897.
Mitochondria is commonly called the “Power house of the cell” because here the energy is stored in form of ATP.
Mitochondria. is present in those cells where the energy requirement is maximum.
The number of mitochondria. varies from cell to cell. Generally in case of liver cells, the number of mitochondria is much more than the other cells.
The mitochondria is absent in case of prokaryotic .
In case of chlamydomonas, only one mitochondria is present. But the muscle cells of insect have 5 lakhs.

The word mitochondrion is derived from two Greek words (mitos meaning thread and chondrion meaning granules ). Hence, mitochondria are short rods or filament like structures found inside a cell cytoplasm.
However, mitochondria have different shapes in different cells. In kidney cells the mitochondria are oval while yeast cells the mitochondria are circular.
The mitochondria is covered by a double layered membrane . Inner layer and outer
layer.
The outer layer is called outer membrane while the inner layer is called inner
membrane.
The space that present between the outer membrane and inner membrane is called
the perimitochondrial space.
The inner membrane is folded into some finger like projections called “crista”.
In the inner membrane, some pin headed structures are present which are called
oxysome particle/F0-F1 particle.
Each oxysome consists of three parts i.e. a base, a stalk and a head.
The inner membrane encloses a space which is called the matrix.
The matrix part of mitochondria contains small, circular, extra-chromosomal D.N.A. called the plasmids and ribosome (70S).
Mitochondrion is called as semiautonomous organelle and power house of the cell.

Mitochondrion is the main site of cellular aerobic respiration
The TCA cycle occurs in mitochondria matrix.
In the mitochondria, the oxidation of fatty acid occurs
Mitochondria stores some amount of cellular energy in form of ATP( energy currency), due to which it is called the “power house of the cell”.
Electron transport chain (ETS) takes place Inside the mitochondria.
Mitochondrion is also called a semi-autonomous particle because it has the DNA and ribosome. Due to presence of mt DNA and ribosomes it has the capacity to reproduce itself.
It also helps in inheritance of cytoplasmic characters (cytoplasmic inheritance).