What is mitochondrial DNA?
Mitochondrial DNA (mtDNA) is located in each cell, outside of the cell’s nucleus. Almost every call in our bodies contains hundreds to thousands of copies of the mtDNA molecule.
A mother’s egg, contains MTDNA, which is passed down from the mother to all of her children. Only daughters will pass mtDNA to the next generation. Men have mtDNA , but they do not pass it down to their children. A child, therefore, inherits mtDNA only from his or her mother.
Although most DNA is packaged in chromosomes within the nucleus, mitochondria also have a small amount of their own DNA. This genetic material is known as mitochondrial DNA or mtDNA.
Mitochondria (illustration) are structures within cells that convert the energy from food into a form that cells can use. Each cell contains hundreds to thousands of mitochondria, which are located in the fluid that surrounds the nucleus (the cytoplasm).
Mitochondria produce energy through a process called oxidative phosphorylation. This process uses oxygen and simple sugars to create adenosine triphosphate (ATP), the cell’s main energy source. A set of enzyme complexes, designated as complexes I-V, carry out oxidative phosphorylation within mitochondria.
In addition to energy production, mitochondria play a role in several other cellular activities. For example, mitochondria help regulate the self-destruction of cells (apoptosis). They are also necessary for the production of substances such as cholesterol and heme (a component of hemoglobin, the molecule that carries oxygen in the blood).
Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation. The remaining genes provide instructions for making molecules called transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), which are chemical cousins of DNA. These types of RNA help assemble protein building blocks (amino acids) into functioning proteins.
Adenosine Triphosplate – (ATP) is a nucleotide also called a nucleotide tripphospate, is a small molecule used in a coenzyme. It is often referred to as the “molecule unit of currency” of intercellular energy transfer. (This can be more technical for most readers to understand so look for in the intermediate and advance chapters in the future.
Oxidative phosphorylation – (for OXPHOS) is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy which is used to reform ATP. This takes place inside of the mitochondria.