STD-11 UNIT-3 CHA-8
CELL : STRUCTURE AND FUNCTIONS
Autonomy of Mitochondria
- Mitochondria show a large degree of autonomy or independence in their functioning
- Mitochondria have their own DNA which can replicate independently.
- Mitochondrial DNA produces its own mRNA, RNA and rRNA.
- The organelles possess their own ribosomes.
- Mitochondria synthesise some of their own structural proteins.
- However, most of the mitochondrial proteins are synthesised under instructions from cell nucleus.
- The organelles synthesise some of the enzymes required for their functioning.
- They grow internally.
- New mitochondria develop by division/binary fission of pre-existing mitochondria.
- However, mitochondria are not fully autonomous.
- Both their structure and functioning are partially controlled by nucleus of the cell and availability of materials from cytoplasm.
- Mitochondria are believed to be symbionts (Margulis, 1971) in the eucaryotic cells which became associated with them quite early in the evolution.
- Mitochondria are miniature biochemical factories where food stuffs or respiratory substrates are completely oxidised to carbon dioxide and water. The energy liberated in the process is initially stored in the form of reduced coenzymes and reduced prosthetic groups The latter soon undergo oxidation and form energy rich ATP. ATP comes out of mitochondria and helps perform various energy requiring processes of the cell like muscle contraction, nerve impulse conduction , biosynthesis , membrane transport , cell division , movement, etc.Because of the formation of ATP , the mitochondria are called power houses of the cell.
- Mitochondria provide important intermediates for the synthesis of several biochemicals like chlorophyll, cytochromes, pyrimidines, steroids, alkaloids, etc.
- The matrix or inner chamber of the mitochondria has enzymes for the synthesis of fatty acids.Enzymes required for the elongation of fatty acids have been reported in the outer mitochondrial chamber.
- Synthesis of many amino acids occurs in the mitochondria. The first formed amino acids are glutamic acid and aspartic acid . They are synthesised from a - ketoglutaric acid and oxaloacetic acid respectively. Other amino acids are produced by transformation and tran samination or transfer of amino group ( -NH ) from glutamic acid and aspartic acid
- Mitochondria may store and release Calcium when required
- An organism generally receives mitochondria from its mother (maternal inheritance).
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