Network analysis of mitochondrial genome

Abstract

The mitochondrion plays a vital role in the life of unicellular to multicellular organisms by providing energy and heat as it is a site of various metabolic reactions. Mitochondria also have a unique feature which is the presence of its own genome. This unique feature is further amplified by their maternal inheritance only in higher organisms. These features make mitochondria a super-cell organelle. It is the main site of energy production, it has its own circular DNA molecules, and it is inherited in the next generation through females only (uniparental inheritance). The mitochondrial genome is a circular DNA molecule with 16,569 base pairs and harbors thirteen protein-coding genes, two rRNA genes, 22 tRNA genes, and one D-loop or Control region. The control region regulates the replication and transcription of the genome. The thirteen protein-coding genes express the proteins which are involved in oxidative phosphorylation, the energy-producing set of reactions, along with the other proteins which are produced by nuclear genes. Due to its small size, high mutation rate, and lack of recombination, the mitochondrial genome is a useful resource in studying genetic evolution and population genetics. Mitochondrial variations are employed to define various haplogroups, which help in the categorization of the human population according to their migratory and evolutionary path. In general, the individual mutations could be lethal for an individual and force natural selection leading to a selective sweep in the population. However, most of the mutations do not impose any change at the phenotypic level.