Mitochondria

Mitochondria:

The  mitochondria also   called the “power houses” of the cell. Without them, cells would be unable to extract enough energy from  the nutrients, and essentially all cellular functions would cease. Mitochondria are present in all areas of each cell’s cytoplasm, but the total number per cell

varies from  less than a hundred up to several thousand, depending  on the amount of energy required by the cell. Further, the mitochondria are concentrated in those portions of the cell that are responsible for the major share of  its energy metabolism. They are also variable in size  and

shape. it  composed  mainly of two lipid  bilayer –protein membranes:

 an outer membrane and  an inner membrane. Many infoldings of the inner  membrane form shelves onto which oxidative enzymes are attached;  the inner cavity of the mitochondrion  is filled with a matrix that contains large quantities of dissolved enzymes that are necessary for extracting energy from nutrients.  

These enzymes operate in association with the oxidative enzymes on the shelves to cause oxidation of the nutrients, thereby forming carbon  dioxide and water and at the same  time releasing energy. The liberated energy is used to synthesize a “high-energy” substance called adenosine triphosphate (ATP).ATP is then transported out of the mitochondrion, and it diffuses throughout the cell to  release its own energy wherever it is

      

needed for performing  cellular function. Mitochondria are self replicative, which means that one mitochondrion can form a second one, a third one, and so on, whenever there is a need in the cell for increased amounts of ATP. Indeed, the mitochondria contain DNA similar to that found in the cell nucleus. The DNA of the mitochondrion plays a  role in  controlling replication of the mitochondrion itself.