![What do mitochondria do? Mitochondria produce almost all of the chemical energy that cells need for all of their functions. Without the mitochondria, we can’t do anything.
The word “mitochondria” was created in 1898 by a microbiologist called Carl Benda. He took the Greek word “mitos”, which means “thread”, and “khondrion”, which means “little granule”. Mitochondria is the plural form of the word. The singular form is mitochondrion. Carl Benda wasn’t the first person to discover mitochondria. They had first been observed by another German microbiologist called Albert von Kölliker. Kölliker was one of the first people to use a light microscope and Carl Benda used microscopes a lot, which rapidly became the new way of observing living organisms. He observed the mitochondria forming long chains, but he didn’t know what they did. Their purpose was only discovered in 1925. So, what do mitochondria do?
Mitochondria probably evolved from independent bacteria. This is just a theory, but the thinking is that mitochondria were prokaryotic cells that were eaten by other cells. Prokaryotic cells are single celled organisms that don’t have a nucleus. They are able to produce energy and reproduce. They were probably eaten as food by eukaryote cells, which are single cells that do have a nucleus. At some point, the two developed a symbiotic relationship. The mitochondria were able to provide energy for the host cells and the host cells provided the mitochondria with food. So, the mitochondria in all of our cells were probably bacteria at some point, although, billions of years ago.
Mitochondria have several functions. They produce energy for cell functions. The trigger cell death when a cell is ready to die. They regulate aging. They are very small. Each one is between 0.75 and 3 micrometers. A hair is about 80 micrometers.
We have more than one mitochondria in each cell. There are up to 1,000. They move around in the cell and they can work in small groups, or they can combine to work in larger groups, depending on the task. They change shape to deal with the kind of nutrient they are going to eat. We have trillions and trillions of them in our bodies. Different types of cells have different numbers of mitochondria. Mature red blood cells don’t have any and liver cells have 2,000. The more energy a cell needs, the more mitochondria it has. Mitochondria can reproduce by cell division, just like bacteria, and when more are needed, they increase their numbers.
The most important job for mitochondria, and probably the reason they ended up living inside our cells, is producing energy. When we eat food, it contains a lot of energy. That energy has ultimately come from the sun, been photosynthesized by plants, and then we either eat the plants or eat animals that have eaten the plants. However, we can’t directly use that energy to carry out processes in our bodies. The mitochondria convert that chemical energy into an energy form called adenosine triphosphate (ATP). This is the energy that our cells can use. The chemical energy is glucose and mitochondria oxidize the parts of the the glucose to make ATP, which powers all of the processes in our cells.
Mitochondria also play a large role in cell death. Mitochondria release a protein called cytochrome c as they work. Once this protein has built up to significant levels, it triggers the cell to begin the process of shutting down. It seems odd that they would trigger cell death when that death will kill them as well. It seems that they do it to protect the overall organism. When there are too many damaged mitochondria, or when there is too much damage in a cell, the mitochondria can not function properly. This is when levels of cytochrome c really build up. It seems that the mitochondria have evolved to remove themselves when there is too much damage. I guess, we are the same.
Mitochondria are also responsible for absorbing calcium and then holding it until it is needed. Our bodies need calcium for chemical activity in the nerves and muscles. Mitochondria help by hanging on to it for us. They can also warm us up when we are cold. When they burn glucose, they produce heat, which is why we get hot when we exercise. They can also create heat by burning brown fat. Adults don’t have a lot of brown fat, but mitochondria can use it when your core body temperature drops. Babies have a lot more brown fat than adults do. Mitochondria have a lot of functions.
Sources
https://www.genome.gov/genetics-glossary/Mitochondria
https://www.medicalnewstoday.com/articles/320875#disease
https://medschool.ucla.edu/research/themed-areas/metabolism-research/mitochondria
https://en.wikipedia.org/wiki/Mitochondrion
https://en.wikipedia.org/wiki/Apoptosis
https://bscb.org/learning-resources/softcell-e-learning/mitochondrion-much-more-than-an-energy-converter/
https://www.reddit.com/r/biology/comments/bfpbiu/how_was_mitochondria_integrated_to_the_host_cells/
https://en.wikipedia.org/wiki/Carl_Benda
https://www.etymonline.com/word/mitochondria
Image By Mariana Ruiz Villarreal LadyofHats - the diagram i made myself using adobe illustrator. as a source for the information i used the diagrams found here:[1], [2], [3], [4], [5], [6] and [7]., Public Domain, https://commons.wikimedia.org/w/index.php?curid=6195050](https://ilearnedthistoday.com/wp-content/uploads/2025/04/Animal_mitochondrion_diagram_en.png)
What do mitochondria do? Mitochondria produce almost all of the chemical energy that cells need for all of their functions. Without the mitochondria, we can’t do anything.
The word “mitochondria” was created in 1898 by a microbiologist called Carl Benda. He took the Greek word “mitos”, which means “thread”, and “khondrion”, which means “little granule”. Mitochondria is the plural form of the word. The singular form is mitochondrion. Carl Benda wasn’t the first person to discover mitochondria. They had first been observed by another German microbiologist called Albert von Kölliker. Kölliker was one of the first people to use a light microscope and Carl Benda used microscopes a lot, which rapidly became the new way of observing living organisms. He observed the mitochondria forming long chains, but he didn’t know what they did. Their purpose was only discovered in 1925. So, what do mitochondria do?
Mitochondria probably evolved from independent bacteria. This is just a theory, but the thinking is that mitochondria were prokaryotic cells that were eaten by other cells. Prokaryotic cells are single celled organisms that don’t have a nucleus. They are able to produce energy and reproduce. They were probably eaten as food by eukaryote cells, which are single cells that do have a nucleus. At some point, the two developed a symbiotic relationship. The mitochondria were able to provide energy for the host cells and the host cells provided the mitochondria with food. So, the mitochondria in all of our cells were probably bacteria at some point, although, billions of years ago.
Mitochondria have several functions. They produce energy for cell functions. The trigger cell death when a cell is ready to die. They regulate aging. They are very small. Each one is between 0.75 and 3 micrometers. A hair is about 80 micrometers.
We have more than one mitochondria in each cell. There are up to 1,000. They move around in the cell and they can work in small groups, or they can combine to work in larger groups, depending on the task. They change shape to deal with the kind of nutrient they are going to eat. We have trillions and trillions of them in our bodies. Different types of cells have different numbers of mitochondria. Mature red blood cells don’t have any and liver cells have 2,000. The more energy a cell needs, the more mitochondria it has. Mitochondria can reproduce by cell division, just like bacteria, and when more are needed, they increase their numbers.
The most important job for mitochondria, and probably the reason they ended up living inside our cells, is producing energy. When we eat food, it contains a lot of energy. That energy has ultimately come from the sun, been photosynthesized by plants, and then we either eat the plants or eat animals that have eaten the plants. However, we can’t directly use that energy to carry out processes in our bodies. The mitochondria convert that chemical energy into an energy form called adenosine triphosphate (ATP). This is the energy that our cells can use. The chemical energy is glucose and mitochondria oxidize the parts of the the glucose to make ATP, which powers all of the processes in our cells.
Mitochondria also play a large role in cell death. Mitochondria release a protein called cytochrome c as they work. Once this protein has built up to significant levels, it triggers the cell to begin the process of shutting down. It seems odd that they would trigger cell death when that death will kill them as well. It seems that they do it to protect the overall organism. When there are too many damaged mitochondria, or when there is too much damage in a cell, the mitochondria can not function properly. This is when levels of cytochrome c really build up. It seems that the mitochondria have evolved to remove themselves when there is too much damage. I guess, we are the same.
Mitochondria are also responsible for absorbing calcium and then holding it until it is needed. Our bodies need calcium for chemical activity in the nerves and muscles. Mitochondria help by hanging on to it for us. They can also warm us up when we are cold. When they burn glucose, they produce heat, which is why we get hot when we exercise. They can also create heat by burning brown fat. Adults don’t have a lot of brown fat, but mitochondria can use it when your core body temperature drops. Babies have a lot more brown fat than adults do. Mitochondria have a lot of functions.
Sources
https://www.genome.gov/genetics-glossary/Mitochondria
https://www.medicalnewstoday.com/articles/320875#disease
https://medschool.ucla.edu/research/themed-areas/metabolism-research/mitochondria
https://en.wikipedia.org/wiki/Mitochondrion
https://en.wikipedia.org/wiki/Apoptosis
https://en.wikipedia.org/wiki/Carl_Benda
https://www.etymonline.com/word/mitochondria
Image By Mariana Ruiz Villarreal LadyofHats – the diagram i made myself using adobe illustrator. as a source for the information i used the diagrams found here:[1], [2], [3], [4], [5], [6] and [7]., Public Domain, https://commons.wikimedia.org/w/index.php?curid=6195050