All You Need To Know About Mitochondria – The Definition, Importance, Discovery, And Function

Widely known for how they generate adenosine triphosphate (also known as ATP) via aerobic respiration, mitochondria play a crucial role in every cell.

They provide several other functions which can vary depending on how diverse the eukaryotic lineage is.

All You Need To Know About Mitochondria - The Definition, Importance, Discovery, And Function

However, regardless of all this diversity, mitochondria derive from an ancestral organelle which comes from the integration of alphaproteobacterium, which is an endosymbiotic, into a host cell which is related to Asgard archaea.

That one transition alone helped create new genes, a system to import protein, genome reduction, and the integration of reproduction and metabolism.

In this guide, we will look at the definition of mitochondria, why it is so important, its discovery, and its function.

The Definition Of Mitochondria

Every single living organism has a central nucleus which forms the cell, Mitochondria are commonly known as the powerhouses of the cell. They are the subcellular, cylindrical organelles that are located in eukaryotes.

As special compartments located in our cells, mitochondria break down food molecules and churn out ATP which is a molecular fuel that powers the rest of the cell.

Mitochondria are comprised of an inner and outer membrane, an intermembrane space, the matrix, and the cristae.

The outer membrane is considered more porous than most molecules and smaller molecules can pass through while the area hosts many enzymes that perform several functions.

The inner membrane is where most of the ATP is created and also contains proteins yet is tightly sealed and this is partly due to its lack of porins (a type of protein) compared to the outer membrane.

As the inner membrane is more or less impermeable to the vast majority of molecules, they can only cross via special membrane transporters.

An intermembrane space separates the outer from the inner membrane. Then there is the matrix which represents the space found inside the inner membrane containing mitochondrial DNA and has enzymes that run into the hundreds which are important for how ATP is produced.

Finally, the cristae are the folds within the inner membrane that increase its surface area and provide more space for the chemical reactions that occur.

Being membrane-bound with not one but two separate membranes is a little odd for an intercellular organelle.

Both the inner and outer membrane provide a function for the mitochondria and its production of energy.

What also defines mitochondria is how highly dynamic they are to respond to demands in energy and their ability to fuse, divide, then form extensive networks within the cell.

Another defining characteristic of mitochondria is how they contain their own genetic material known as mitochondrial DNA. This is inherited from the mother and is an important feature to remember.

This is due to how genomic DNA found in the cell’s nucleus and any mutations found in the mitochondrial DNA can result in dysfunctional mitochondrial DNA or the absence of it altogether.

If that’s the case then you can expect primary mitochondrial diseases that can have different effects on the body’s organs, be very variable at the start and have different levels of severity.

The Importance Of Mitochondria

All You Need To Know About Mitochondria

Whenever you need energy, mitochondria are there in the vital areas of your muscle cells. This is where protein, carbohydrates, and fat are broken down with oxygen, producing the energy required for cell function and aerobic exercise.

For ocular function, mitochondria are vital to represent the origin of a cell’s energy supply, maintain differentiation, and keep that cell surviving.

Combat Heart Disease

If your mitochondria are functioning as they should, they can go some way to avert heart disease. This is due to how the mitochondria assist in regulating the function of cardiovascular cells.

On the other hand, any dysfunction with mitochondria can add up to an increased danger of cardiovascular illness.

Maintain Blood Sugar Level

A reduced number, capacity, and biogenesis of mitochondria have been found in a high proportion of patients that have type 2 diabetes.

This is related to mitochondria and its involvement with breaking down nutrients and molecules into energy.

During the creation of insulin in the pancreatic beta cells, mitochondria have an essential role to maintain blood sugar levels.

Improving Athletic Performance

When you are performing physical exercise, you need a few things apart from the right training gear. A sense of perseverance to keep going should help you improve your time when running a certain distance, for instance.

What also helps is how long it takes for your body to produce energy from oxygen and sugar in the muscles that you are working.

This is where mitochondria come in to enhance that generation of energy when more is required from your muscle cells to enhance and improve your athletic performance.

Fat Loss

Anyone wanting to lose weight should be thankful for their mitochondria. An increased number of them will produce an increase in energy derived from glucose, amino acids, and, ultimately, fat.

With the mitochondria working, you should consume more calories with a reduction in fat.


When mitochondria begin to fail and become extremely dysfunctional, this is usually at the time of untimely aging and, eventually, death.

The mitochondria are essential for several biological processes so if they keep functioning, your body will function to an extent too.

Due to how mitochondria are practically embedded in how a cell functions, once they begin to dysfunction they can become involved in how very complex secondary diseases develop.

These can include neurodegenerative disorders, cancer, strokes, and heart diseases.

The Discovery Of Mitochondria

Mitochondria were first discovered in 1898 when they were named during a study of cell internal structure by Carl Benda.

It took until 1904 for information about mitochondria to be first recorded about their work in plants in cells by Friedrich Meves.

Four years later, Meves and Claudius Regaud demonstrated that mitochondria contain lipids and proteins. Two speculations were made from their discovery which were endosymbiotic and autogenous.

According to the autogenous hypothesis, the mitochondria formed when a part of DNA was separated from the eukaryotic cell’s nucleus.

This was while the prokaryotes were branching out and the segment of DNA was confined by membranes. These membranes could not be crossed by proteins which should have made them stand out.

The endosymbiotic speculation was a little different in demonstrating that mitochondria are initially prokaryotic cells.

These are ideal for the execution of oxidative components which are typically unrealistic for those eukaryotic cells.

They actually developed into endosymbionts which resided in the eukaryotes. As mitochondria share plenty of characteristics that are similar to bacteria, it is the endosymbiotic hypothesis which is typically accepted.

One of the telltale reasons why mitochondria are believed to have originated from bacteria is how they contain a tiny bit of DNA.

This DNA is close to bacterial DNA while the mitochondrial DNA has a length of about 16,000 bases with 37 genes throughout individuals.

The Function Of Mitochondria

All You Need To Know About Mitochondria

Mitochondria play a vital role in how every human body functions and produces energy via cellular respiration.

The organelles shape themselves like a rod, pick the nutrients of a cell, and help create about 90% of the energy which the cell requires to chemically survive.

The more energy a cell requires, the more mitochondria it should have to carry out the function. Should a cell require more energy than remains, more can be produced to fit the requirement.


Mitochondria are there to look after a cell and power its function. They effectively safeguard the cell and its survival while remaining convenient to help with the apoptosis process when required.

Cell Function

For the cell to function properly, mitochondria are essential. They break down, then synthesize, and recycle the bio-chemicals that each cell needs.

Proteolytic Activity

In amoeba, pieces and remnants of immersed food circulate around the cytoplasm and then get related to mitochondria.

Within the pancreas, mitochondria play a vital function in being in charge of the creation of zymogen granules. In protozoa, the mitochondria demonstrate proteolytic enzyme activity which is both lytic and synthetic.

Cellular/Aerobic Respiration

The main job of mitochondria is to convert glucose to energy through aerobic or cellular respiration.

This process uses a combination of water and oxygen where food is transformed into tiny molecules and nutrients. Air comes in then the smallest of nutrients and molecules are transported into the bloodstream.

Once these molecules and nutrients are broken down, they are made up of oxygen and glucose. Where mitochondria provide a function, it is to act as heaters to stoke a fire.

Just like fire burns up oxygen and then emits water with carbon dioxide, mitochondria produce adenosine triphosphate (ATP) from the glucose while also using oxygen which emits carbon dioxide and water.

This process is known as an aerobic one and this chemical procedure is respiration which occurs in every cell and should specify it as aerobic cellular respiration.

During the process, primary cell function is achieved which is demonstrated by the tricarboxylic acid cycle or the Krebs cycle.

In plants, mitochondria work with chloroplasts to create a genetic print on material and act for controlling ecological factors.

This is a separate process to producing energy to help the cells function naturally as this is done with chloroplasts during the photosynthesis process to complete the last three stages during cellular respiration.

A range of cells can have different numbers of mitochondria based on its function. Muscle has a lot, as does the kidney and liver.

The brain also has lots of mitochondria and uses the energy to function. Should you have a problem with the pathways then the mitochondria will dysfunction, as will the organ or muscle that is being supplied.

This can result in a range of different symptoms, depending on where it occurs in the body and there is still research being carried out on this issue.

Aside from energy production, mitochondria also have several functions that work for the overall wellbeing of human cells.

Mitochondria produce other chemicals such as those that break down waste products to reduce their harm and then recycle some waste to conserve energy.

As self-producing organelles, mitochondria reproduce when physiological necessity demands.

With essential enzymes, ribosomes, and DNA, mitochondria maintain both protein synthesis and phospholipids synthesis with several little molecular weight constituents too.

Frequently Asked Questions

Do Mitochondria Contain DNA?

Found in the cytoplasm, mitochondria are where a cell’s energy is produced as well as other functions for metabolism. They do in fact contain DNA which is contained in the cells.

The mitochondria from a mother come from the sexual reproduction where, during fertilization, only the nuclear DNA ends up in the egg cell which a lot of everything else is destroyed.

Through this process, an individual’s offspring inherit the mitochondria, and the mitochondrial DNA, from the mother.

Where Do Mitochondria Originate From?

The origin of mitochondria comes from the evolution of an endosymbiotic alphaproteobacterium which would have come from an archae-derived host cell. This host cell was most likely related to the Asgard archaea.

You can expect mitochondria’s earliest ancestor to be the pre-mitochondrial alphaproteobacterium, unless it was an ancestor of an extant alphaproteobacterium.

Final Thoughts

As the powerhouses of the cell, mitochondria are vital to convert energy from the food we eat into energy that the cell can use.

Mitochondria’s function goes beyond that as they can signal between cells, help safeguard the cell, and be involved in fat loss and combating heart disease.

All mitochondria typically measures from 0.75 to 3 micrometers and cannot be visible under a microscope but each one provides a vital function.

Jennifer Dawkins

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