Definition
Every body cell has certain functional units, so-called cell organelles. They are the small organs of the cell and, like the large organs, have assigned areas of responsibility. Mitochondria and ribosomes belong to the cell organelles.
The function of the cell organelles is different; some produce building material, others provide for order and clean up the “garbage”. Mitochondria are responsible for energy supply. For many years, they have been known as the “power plants of the cell”.
They bring together all the necessary components for energy production in order to produce biological energy suppliers for all processes through so-called cell respiration. Each body cell has an average of 1000-2000 individual mitochondria, making up about a quarter of the entire cell. The more energy a cell needs for its work, the more mitochondria it usually has. This is why nerve and sensory cells, muscle and heart muscle cells are among those that are richer in mitochondria than others, because their processes run virtually permanently and are extremely energy-intensive.
Structure of a mitochondrion
The structure of a mitochondrion is quite complex compared to other cell organelles. They are about 0.5 μm in size, but can also grow larger. A mitochondrium has two shells, a so-called outer and an inner membrane.
The membrane has a size of about 5-7nm. These membranes are different. The outer one is oval like a capsule and is permeable for substances due to its many pores.
The inner one, on the other hand, forms a barrier, but can selectively let substances in and out through many special channels. Another special feature of the inner membrane compared to the outer membrane is its folding, which ensures that the inner membrane protrudes into the interior of the mitochondrion in countless narrow indentations. This makes the surface area of the inner membrane significantly larger than that of the outer membrane. This structure creates different spaces within the mitochondrion, which are important for the different steps of energy production, including the outer membrane, the space between the membranes including the indentations (so-called Christae), the inner membrane and the space within the inner membrane (so-called matrix, it is only surrounded by the inner membrane).
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