What is the function of mitochondrial DNA?

Mitochondrial DNA (mtDNA) is responsible for encoding proteins essential for the mitochondria's energy-producing function.

Mitochondrial DNA, often abbreviated as mtDNA, is a small circular strand of DNA found within the mitochondria of eukaryotic cells. Unlike nuclear DNA, which is inherited from both parents, mtDNA is maternally inherited. This means it is passed down from mother to offspring.

The primary function of mtDNA is to encode proteins that are essential for the mitochondria's primary role: energy production. The mitochondria, often referred to as the 'powerhouse of the cell', are responsible for generating adenosine triphosphate (ATP), the cell's main source of energy. To do this, they use a process called oxidative phosphorylation, which involves a series of chemical reactions that require specific proteins. These proteins are encoded by the mtDNA.

The mtDNA is made up of approximately 16,569 base pairs, which encode for 37 genes. 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 needed to produce proteins within the mitochondria.

It's also worth noting that mtDNA has a high mutation rate compared to nuclear DNA. This is due to the lack of protective histones, the proximity to reactive oxygen species produced during ATP synthesis, and limited DNA repair mechanisms. These mutations can lead to mitochondrial diseases, which are often characterised by muscle weakness and problems with growth and development.

In summary, the function of mitochondrial DNA is to encode proteins that are essential for the mitochondria's energy-producing function. Without mtDNA, the mitochondria would not be able to produce ATP efficiently, which would have severe consequences for the cell's energy supply.