Mitochondria

Biologists from Centre for Cellular and Molecular Biology, Hyderabad (CCMB), have conducted a study to understand how mitochondria became an inseparable part of animal and plant cells.

Today, mitochondria are well known to be integral parts of the eukaryotic cell.
They are dubbed the power houses of the cell, because they help in generating energy in the form of ATP within the cell, powering it.
But they were not always part of the animal and plant cells.

Mitochondria were not always part of the animal and plant cells. Once, about two billion years ago, a prokaryotic organism (without a nucleus) called archaea captured a bacterial cell. The bacterial cell learnt to live within the archaea as an endosymbiont.
- Endosymbionts are organisms that form a symbiotic relationship with another cell or organism.
In the late 19th century, microscopists observed that organelles like chloroplast [and later mitochondria] undergo division inside eukaryotic cells that resembles bacterial division, which led them to suspect that these organelles might have arisen from bacterial endosymbionts.
By studying an organism known as jakobid, which has been around since before animals and fungi branched off from plants and algae in the process of evolution, the researchers have identified two adjustments that had to take place to facilitate the integration of the two organisms.
These adjustments were made in the process of optimisation when the two organisms merged together, evidently for compatibility. The researchers show that these changes, in a protein (DTD) and a tRNA (carrying an amino acid glycine for protein synthesis) are crucial for the successful emergence of mitochondria.

- Mitochondria are membrane-bound cell organelles that generate most of the chemical energy needed to power the cell’s biochemical reactions.
- Mitochondria are known as the powerhouse of the cell.

Chemical energy produced by the mitochondria is stored in a small molecule called adenosine triphosphate (ATP).
ATP is known as the energy currency of the cell.
Mitochondria contain two membranes, rather than simply one.
The exterior membrane is very porous, but the inner membrane is tightly folded. These folds provide a wide surface area for chemical processes that generate ATP.
Mitochondria have their own DNA and ribosomes. As a result, mitochondria can produce some of their own proteins. Both mitochondria and chloroplasts contain their own DNA and ribosomes.
Mitochondria contain their own small chromosomes. Generally, mitochondria, and therefore mitochondrial DNA, are inherited only from the mother.

Prokaryotic and Eukaryotic cells

All life on Earth consists of either eukaryotic cells or prokaryotic cells. Prokaryotes were the first form of life.
Eukaryotes are organisms whose cells contain a nucleus and other membrane-bound organelles. Example- Protozoa, fungi, plants, and animals
Prokaryotes are organisms whose cells lack a nucleus and other organelles.
Prokaryotes do not have mitochondria. Mitochondria are only found in eukaryotic cells.
Eukaryotes may be either single-celled or multicellular.

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