Mitochondria: function and structure

The mitochondria is one of the most important organelles in the eukaryotic cell. Within it, important processes are carried out in an exact machinery in which different proteins, molecules, channels and membranes intervene. It is so advanced that it has even been postulated that it originated from a prokaryotic cell that engulfed an aerobic bacterium millions of years ago.

Interesting: How do fungi reproduce

What are mitochondria

Mitochondria, sometimes known as chondriosomes, are highly specialized organelles found in the cytoplasm of eukaryotic cells, including animals, plants, fungi, and protists. They are small units within the cell that carry out specific functions for their development . They are associated with the cell membrane with the help of a double membrane. The shape of this organelle can be different depending on the type of cell in question, and can be like rods, long filaments or granules.

The number of mitochondria varies according to their cell type, because there are cells or tissues that have a much greater energy demand, such as muscle, brain or liver.

What are mitochondria: Function of the mitochondria

10 functions/Role of: mitochondria: Two important processes occur within the mitochondria: cellular respiration through the use of oxygen, and the production of chemical energy necessary for the cell to carry out its biochemical reactions. Next, we will see them in more detail.

  • 10 functions/Role of: mitochondria: Cellular respiration using oxygen : These are the Krebs cycle, a metabolic pathway in which energy is released by the oxidation of acetyl coenzyme A, the aforementioned oxidative phosphorylation process, and the electron transport chain.
  • 10 functions/Role of: mitochondria: Chemical energy production : it is stored in the form of ATP or adenosine triphosphate, since this phosphate generates a high-energy bond. This ATP is catalyzed with the help of the transmembrane enzyme ATP synthase, from the oxidation of amino acids, fatty acids and sugars, and this is what is known as oxidative phosphorylation.

Role of mitochondria: In the inner membrane of the mitochondria there are enzymatic complexes composed of several proteins that have multiple activities:

  • Use of molecular oxygen .
  • Reduction and oxidation of different organic compounds : in this way a chain is formed through which electrons are transported.
  • Pumping of electrons : towards the mitochondrial intermembrane space.

These respiratory chain complexes are divided into complex I or NADH dehydrogenase, complex II or succinate dehydrogenase, complex III or coenzyme Q-cytochrome c reductase, and complex IV or cytochrome oxidase.

What are mitochondria: Structure of the mitochondria

Structure of mitochondria: Although the structure of mitochondria can be variable, the following parts are usually found.

Outer membrane

The mitochondria are delimited from the outside with their outer membrane, which allows them to be communicated at the same time. It receive a lot of information from the cell and for this they have proteins with holes called porins to allow the passage of ions and other smaller proteins into the intermembrane space. All the proteins that enter must be unfolded, which happens thanks to the chaperone proteins. They are also helped by protein complexes to introduce proteins. mitochondria function in plant cell

Inner membrane

Inside, the mitochondria have an inner membrane that forms the matrix, arranged within the inner membrane. It is analogous to the cytoplasm of the cell . From this region comes energy in the form of ATP. Here metabolic processes occur such as:

  • Oxidative phosphorylation.
  • the production of ATP.
  • The Krebs cycle.
  • The oxidation of pyruvate.
  • The oxidation of amino acids.
  • The oxidation of fatty acids.

It also has a structural function because it is here where the other micro-organelles of the mitochondria are arranged, such as ribosomes, DNA, ions, and metabolites. The inner membrane is made up of a lipid bilayer where there are enzymatic complexes made up of different proteins necessary for the electron transport chain.


Structure of mitochondria: The outer and inner membranes fold to form cristae, in the form of folds. They are located mainly at the edges of the it, but bounded outwards by the outer membrane. They are arranged perpendicular to the boundary of the mitochondria. The most important functions of the mitochondria occur in the membranes of these cristae :

  • Electron transport: with the help of enzyme complexes that transfer electrons from one site to another.
  • Oxidative phosphorylation.
  • The compact and the maximization of electron transfer.

Mitochondrial intermembrane space

Between the inner and outer membrane there is a space called the mitochondrial intermembrane space, which is of vital importance for cellular activity. It has a high content of enzymes necessary for respiration. Its main function is the reception of electrons from the pumping of enzyme complexes. It is watery in consistency. Here are enzymes and proteins that assist in the cellular process. Translocation also occurs here , a process where mitochondrial matrix proteins are transported from outside the it. Finally, they transport fatty acids.


Mitochondria also have ribosomes, called mitoribosomes or mitochondrial ribosomes, with the same function as ribosomes : to synthesize proteins through gene translation. They receive the information in the form of RNA to translate it into DNA. mitochondria function in plant cell

What are mitochondria: Mitogenome or DNA

Mitochondria have their own DNA. In fact, they are the only organelle with particular DNA . It always works in conjunction with the DNA in the nucleus to achieve coordinated activities and has a small, circular shape. This mitochondrial DNA is inherited only from the mother , not from the father, and not by genetic recombination.

In this mitochondrial DNA, genetic faults can occur with pathogenic results of diseases such as Parkinson’s, due to its proximity to oxidative metabolism. Also, it lacks protective histones , unlike the DNA of the cell nucleus, which does. mitochondria function in plant cell

This DNA has been of great evolutionary interest, as it was explained by the principles of the endosymbiosis theory : where a prokaryotic cell engulfed an aerobically respiring bacterium to obtain its organelles, creating a eukaryotic cell and symbiotic relationship. It is understandable then that the mitochondria is a special organelle with several micro-organelles inside it, as if it were a small cell by itself.

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