Origin of Mitochondria

The origin of mitochondria goes back in time two billion years, when a cell engulfed another one. Yes, a mitochondrion is one pro-karyotic cell living in perfect symbiosis in an eukaryotic cell. This endosymbiotic relationship allowed the proliferation of multi-celled organisms.

Endosymbiotic origin of mitochondrion

In 1970, biologist Lynn Margulis published an endosymbiotic theory of the mitochondrion. About two billion years ago, a cell penetrated another cell and began living forever inside the cytoplasm of its host. This is the perfect symbiosis in biology which made possible the evolution of life on Earth, with single cells evolving into multicellular organisms. This is thanks to the capacity of the intruder cell (the mitochondrion) of consuming free available fuel stuff (pyruvate and acetyl CoA, which are the byproducts of glycolysis and ketolysis) in the cytoplasm, converting them into ATP. Thus, the new energy being produced in great amount influenced the host cell nucleus DNA to split in two, causing the cell to divide into two and proliferate.

As you know, the mitochondrion is an important eukaryotic cell organelle, which generates the vital energy needed by the cell in the form of ATP (Adenosine TriPhosphate) through what is known as cellular respiration. This is the reason, it is often referred to as the cell power plant. The word mitochondrion was first employed in 1898 by the German microbiologist Carl Benda, with “mitos” meaning thread, and “chondros” meaning granule. However, it had already been discovered in 1857 by the Swiss scientist Albert von Kolliker using an optical microscope.

How many mitochondria are there in a cell?

Depending on the type of cell and tissue, the number of mitochondria in their cytoplasm ranges from zero to thousands, with the red blood cells having none and a hepatocyte having more than two thousands.

This very reasonable and logic theory is based on the fact that the mitochondrion has its own DNA material as well as its own ribosomes and membranes that isolate it. When a mitochondrion has good health, that is when it runs efficiently producing enough ATP, its DNA will divide in two, splitting the mitochondrion into two mitochondria. This process is called mitochondrial bioneogenesis, which is only possible in the absence of deleterious free radicals. The more mitochondria in a cell, the more ATP per second there will be; in other words, the faster the metabolism will be.