While studying respiration, the topic of mitochondria came up. Mitochondria are organelles found inside the cells of living organisms, and apparently their role is to use oxygen and nutrients to produce carbon dioxide and ATP, the energy currency. Mitochondria are also known as energy production factories, and living organisms cannot survive without them.
number of mitochondria
Mitochondria are a few micrometers in size, and in humans, on average, there are hundreds to thousands of mitochondria in one cell, with heart cells and brain nerve cells, which use energy, having more than 10,000 mitochondria, and the whole body having more than 1,000 trillion mitochondria. When converted into weight, mitochondria make up 10% of body weight.
The ATP produced by mitochondria is consumed, recycled, and regenerated one after another. The body has about 50g of ATP, which is reproduced many times, resulting in 180kg being produced per day. A maximum of 600 ATP units are produced per second, and one cell contains 1 billion ATP units. If we think of mitochondria as factories, they may never have a day off and be constantly operating at high capacity.
Mitochondria are derived from the mother
Mitochondria have their own DNA, called mtDNA, which is inherited from the mother. The mitochondria from the father are broken down and removed at the time of fertilization, leaving only the DNA from the mother. Even though they have their own DNA, it seems that mitochondria cannot exist alone outside of cells, as some of the necessary information is contained in the DNA of the cell nucleus.
Controlling the life of cells
Mitochondria have outer and inner membranes made of lipids just like cells, and receive nutrients broken down from the glycolytic pathway in the cytoplasm outside the outer membrane, and produce ATP inside the membrane. Inside the inner membrane is a central part called the matrix, where substances produced in the citric acid cycle are sent to the electron transport chain in the inner membrane to produce ATP.
This series of events also has a lifespan, and mitochondria also seem to play a role in turning on the apoptosis switch, which causes cell death by destroying the structures of cells damaged by stress or injury. When the switch is turned on, the mitochondria themselves are decomposed along with cell death.
where did it come from
The outer membrane of mitochondria has a transmembrane protein called a porin, which has a large hole that allows the decomposed nutrients to pass inside and the produced ATP to pass outside. Porins are barrel-shaped, called beta barrels, and are also found in the outer membrane of chlorophyll. In addition, mitochondria and chlorophyll are the only organelles in living organisms that have their own DNA. Mitochondria and chlorophyll have a lot in common.
It is strange that a living organism can have its own DNA in the first place, but this intracellular cell-like existence is also called primary symbiosis, and it seems that it began when the ancestor of eukaryotes absorbed bacteria about 2 billion years ago. It was from this point that living organisms were able to use oxygen to generate energy.
Mitochondria are amazing
Living organisms hardly make their own energy, and seem to rely on mitochondria for most of their energy production. They are so tiny that we can’t see them, but it seems we can live thanks to mitochondria. Mitochondria are amazing. Symbiosis with the Earth is amazing.
