what does the mitochondria do

what does the mitochondria do.Mitochondria are complex organelles found only in eukaryotic cells.Its function is to produce most of the energy of the cells , through the process called cellular respiration.The size, shape, quantity and distribution of mitochondria vary according to cell type. They even have their own genetic material.

what does the mitochondria do

structure of mitochondria

Representation of the scheme of mitochondria

Mitochondria are formed by two lipoprotein membranes, one outer and one inner:

  • Outer membrane: similar to that of other organelles, smooth and composed of lipids and proteins called deporins, which control the entry of molecules, allowing the passage of some relatively large ones.
  • Inner membrane: it is less permeable and has numerous folds, called mitochondrial cristae.

The mitochondrial cristae project into the inner part of the mitochondria, a central space called the mitochondrial matrix, which is filled with a viscous substance where respiratory enzymes that participate in the energy production process are located.

In the matrix are found the ribosomes , organelles that produce proteins necessary for the mitochondria. They are different from those found in the cell cytoplasm and more like that of bacteria. Another characteristic common to bacteria and mitochondria is the presence of circular DNA molecules.

See also: Cell Organelles

Cellular respiration

Cellular Respiration Scheme

Cellular respiration is an oxidation process of organic molecules , such as fatty acids and carbohydrates, especially glucose , which is the main source of energy used by heterotrophic organisms.

Glucose comes from food (being produced by autotrophic organisms through photosynthesis) and converted into carbon dioxide and water, producing molecules of ATP (adenosine triphosphate), which are used in various cellular activities.

This energy production mode is very efficient, as there is a balance of 38 ATP for each glucose molecule at the end of the process.

See too:

  • ATP
  • Energetic metabolism

Glucose degradation involves several molecules, enzymes and ions and takes place in 3 steps: Glycolysis , Krebs Cycle and Oxidative Phosphorylation . The last two phases are the ones that produce the most energy and occur in the mitochondria, while glycolysis takes place in the cytoplasm .

The general chemical equation of the process is represented as follows:

6 H 12 O 6 + 6 O 2  6 CO 2 + 6 H 2 O + Energy

See also: Cell Metabolism

How did mitochondria arise?

Mitochondria have similar biochemical and molecular characteristics to bacteria, such as the presence of circular DNA and ribosomes. For this reason, scientists believe that its origin is related to ancient prokaryotic beings.

According to the Endosymbiotic Theory or Endosymbiogenesis , ancient prokaryotic organisms would have successfully hosted within the eukaryotic cells of primitive organisms, evolving into the current mitochondria.

The same would have happened with chloroplasts , which are similar to mitochondria due to the presence of a double membrane and their ability to self-replicate.

See also : Prokaryotic and Eukaryotic Cells


  • The word mitochondria derives from the Greek, mitos(thread/thread) + chondros (granule/grain).
  • Mitochondria are spherical or elongated and have approximate dimensions of 0.5 to 1 µm in diameter. They can represent up to 20% of the total cell volume.
  • Mitochondrial DNA is of exclusively maternal origin.
  • Mitochondria are also related to the process of cell death by apoptosis.


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