Mitochondria are the cell organelles which produce energy.
They are small sac like structures floating in the cell.
They are the places where tri-carboxylic acid cycle occurs leading to complete break down of glucose into water and carbon-dioxide.
In doing so, they produce energy by oxidative phosphorylation.
A cell cannot survive without mitochondria.
Hence we can expect that mitochondria are present in both plant and animal cells.
Below are some interesting facts on mitochondria.
Mitochondria Facts in cell
1. Single stranded DNA: They have their own cDNA which is single stranded. They can multiply on their own without the involvement of the cell division.
2. Ribosomes: Mitochondria have their own ribosomes. They are few in number and also different in size than regular ribosomes present near the nucleus.
3.Semi-autonomous organelles: Mitochondria are semi-autonomous organelles. They are so called as they can divide on their own and also form proteins without involvement of nucleus.
4. Complex enzymes: They have four complex enzymes which help in its function. These complex include
Complex-I which is a combination of NADH-Q-Reductase. It helps to translocate protons across membranes.
Complex-II is a combination of Succinate-Q-Redcutase made of two polypeptides.
Complex-III is QH2-Cytochrome-C-reducatse.
Complex-IV is Cytochrome-C-Oxidase.
5. Cell death: They are involved in cell death. Mitochondria help in cell death by a process called as apoptosis.
6. Number of mitochondria per cell: Liver cells contains approximately 1600 mitochondria, while kidney cells have 1000 mitochondria, while some oocytes around 300000 mitochondria.
7. Structural changes: Though mitochondria of different cells are similar in an animal, they vary slightly by structure.
The cells of skin have mitochondria which have less folding in the inner membrane to form cristae.
While those of muscle cell have more folding to form more cristae. The more the cristae, the higher is the respiratory capacity and the energy generation.
Mitochondria in diseases:
8. Mitochondrial diseases: Defects in mitochondria can lead to few diseases.
9. Death by poisons: Many poisons cause death due to their action on mitochondrial enzymes. Poisons like heavy metals and cyanide inhibit the function of complexes withing the mitochondria leading to death of animals.
10. Isolation: Though they are very minute in structure, they can be isolated for testing and diagnosis in labs. They have more specific gravity than the cytoplasm. Hence they can be isolated from cells and tissue homogenates by ultra-centrifugation.
They can be observed under microscope by staining with Janus green. Dark field illumination with phase contrast setting helps in viewing them.
Besides above facts, there are more aspects like few drugs are being developed which can act on mitochondria and help in treatment of diseases.
Also the number of mitochondria vary in between plants and animals. Plant cells have less mitochondria than animals cells.