Functions of Mitochondria – Mitochondria are often referred to as the powerhouse of the cell. They help convert the energy we take in from food into energy that cells can use. But, there’s more mitochondria than energy production going on, Grameds.
Present in almost all types of human cells, mitochondria are essential for our survival. They produce most of the adenosine triphosphate (ATP), the energy in the catabolic pathway, aka the energy currency of cells. Mitochondria are also involved in other tasks, such as signaling between cells and cell death, also known as apoptosis.
Through this Gramedia article, we will study the function of mitochondria, their shape, structure, how they work, and their roles in life. Not to forget, we will also learn about what happens if the mitochondria of the cell’s powerhouse stop working properly.
Mitochondria are round to oval shaped organelles found in the cells of almost all eukaryotic organisms. This component produces energy known as ATP for the cell through a series of chemical reactions.
In 1850, Kollicker first observed and isolated mitochondria from cells. This could be due to his observations on the striated muscle tissue of insects. At that time, he found the granules are free structure, and have no direct relationship with the internal structure of the cell.
Linguistically, the term mitochondria itself also comes from a combination of two words, namely Mito and Chodrion which respectively mean thread and granular.
The number of mitochondria per cell varies widely, Grameds. For example, in humans, erythrocytes (red blood cells) do not contain any mitochondria whereas liver cells and muscle cells may contain hundreds or thousands of these components. The only eukaryotic organism known to lack mitochondria is the oxymonas species Monocercomonoides .
Mitochondria are unlike other cellular organelles. The reason is, they have two different membranes, a unique genome, and reproduce by binary fission. These features suggest that mitochondria share an evolutionary past with single-celled organisms.
List of contents
Following are the functions of mitochondria as organelles that are part of this cell. Let’s get acquainted!
Mitochondria Function in Energy Production
The outer mitochondrial membrane is freely permeable to small molecules and contains special channels capable of transporting large molecules. In contrast, the inner membrane is nearly impermeable so that only very small molecules can cross into the gel-like matrix that forms the central mass of the organelle.
This matrix contains deoxyribonucleic acid (DNA) from the mitochondrial genome and enzymes from the tricarboxylic acid cycle (TCA) also known as the citric acid cycle or Krebs cycle, which metabolize nutrients into byproducts that the mitochondria can use for energy production.
Most of the ATP is produced in the mitochondria through a series of reactions. Energy production occurs mostly in the folds or cristae of the inner membrane. Mitochondria convert the chemical energy from our food into a form of energy that cells can use. This process is called oxidative phosphorylation.
The Krebs cycle produces a chemical called NADH. NADH is the substance that enzymes embedded in cristae use to produce ATP. In the ATP molecule, chemical bonds bind energy and store it. When these chemical bonds are broken, energy can be used.
Other Mitochondria Functions
Although the most well-known role of mitochondria is in energy production, they also perform other important tasks. In fact, only about 3 percent of the genes needed to make mitochondria go into their energy-producing apparatus. Most are involved in other work that is specific to the type of cell in which they are found.
Here are some other mitochondrial functions that are important for us to know.
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1. Mitochondria function to regulate cell death
Cell death, also called apoptosis, is an essential part of life. When cells get old or damaged, they are cleaned and destroyed. It is in this case that the mitochondria help decide which cells need to be destroyed.
This component will release cytochrome C which activates caspase , one of the main enzymes involved in cell destruction during apoptosis. In certain diseases, such as cancer, there is damage to normal apoptosis. This makes mitochondria thought to play a role in the disease.
2. Mitochondria function to store calcium
Calcium is essential for a number of processes. For example, releasing calcium back into cells can initiate the release of neurotransmitters from nerve cells or hormones from endocrine cells. Calcium is also needed for muscle function, fertilization, blood clotting, and so on. Other roles of calcium in cells, including regulating cellular metabolism, steroid synthesis, and hormone signaling
Because calcium is considered so important, cells regulate it tightly. Mitochondria in this role absorb calcium ions and hold them quickly until the time calcium is needed.
3. Mitochondria function for heat production
When it’s cold, we shiver to stay warm. However, the body can also generate heat in other ways, one of which is by using a layer called brown fat.
During a process called proton leakage, mitochondria can generate heat. This is known as non-shivering thermogenesis. Brown fat is found at its highest level of 5 percent in infants, when we are more susceptible to cold. The rate slowly decreases with age.
Here are some additional mitochondrial functions:
- Mitochondria have enzymes in liver cells. It works to detoxify ammonia.
- Controls various cycles in cells.
- Builds parts of hormones, such as estrogen or testosterone.
- Supervise the process of differentiation, growth, and development in cells.
- The site of cellular oxidative-respiration metabolic processes.
According to Grameds, what do these tiny, oval-looking mitochondria look like inside? Mitochondria of course still have several other components from the outside to the inside.
Mitochondria are small, often between 0.75 to 3 micrometers and are not visible under a microscope unless stained. Unlike other organelles (mini organs inside the cell), they have two membranes, an outer and an inner one. Each membrane has a different function.