Mitochondrial DNA in the context of "Whole genome sequencing"

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⭐ Core Definition: Mitochondrial DNA

Mitochondrial DNA (mDNA or mtDNA) is the DNA located in the mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the DNA contained in a eukaryotic cell; most of the DNA is in the cell nucleus, and, in plants and algae, the DNA also is found in plastids, such as chloroplasts. Mitochondrial DNA is responsible for coding of 13 essential subunits of the complex oxidative phosphorylation (OXPHOS) system which has a role in cellular energy conversion.

Human mitochondrial DNA was the first significant part of the human genome to be sequenced. This sequencing revealed that human mtDNA has 16,569 base pairs and encodes 13 proteins. As in other vertebrates, the human mitochondrial genetic code differs slightly from nuclear DNA.

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Mitochondrial DNA in the context of Taíno

The Taíno were the Indigenous peoples of the Greater Antilles and surrounding islands. At the time of European contact in the late 15th century, they were the principal inhabitants of most of what is now The Bahamas, Cuba, the Dominican Republic, Haiti, Jamaica, Puerto Rico, and the northern Lesser Antilles. The Lucayan branch of the Taíno were the first New World people encountered by Christopher Columbus, in the Bahama Archipelago on October 12, 1492. The Taíno historically spoke an Arawakan language. Granberry and Vescelius (2004) recognized two varieties of the Taino language: "Classical Taino", spoken in Puerto Rico and most of Hispaniola, and "Ciboney Taino", spoken in the Bahamas, most of Cuba, western Hispaniola, and Jamaica. They lived in agricultural societies ruled by caciques with fixed settlements and a matrilineal system of kinship and inheritance. Taíno religion centered on the worship of zemis. The Taíno are sometimes also referred to as Island Arawaks or Antillean Arawaks. Indigenous people in the Greater Antilles did not refer to themselves originally as Taíno; the term was first explicitly used in this sense by Constantine Samuel Rafinesque in 1836.

Historically, anthropologists and historians believed that the Taíno were no longer extant centuries ago, or that they gradually merged into a common identity with African and Hispanic cultures. Scholarly attitudes to Taíno survival and resurgence began to change around the year 2000. Many people today identify as Taíno and many more have Taíno descent, most notably in Puerto Rico, Cuba, and Dominica. A substantial number of Puerto Ricans, Cubans, and Dominicans have Indigenous mitochondrial DNA, which may suggest Taíno descent through the direct female line, especially in Puerto Rico. While some communities describe an unbroken cultural heritage passed down through the generations, often in secret, others are revivalist communities who seek to incorporate Taíno culture into their lives.

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Mitochondrial DNA in the context of Genome

A genome is all the genetic information of an organism or cell. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of junk DNA with no evident function. Almost all eukaryotes have mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplasts with a chloroplast genome.

The study of the genome is called genomics. The genomes of many organisms have been sequenced and various regions have been annotated. The first genome to be sequenced was that of the virus φX174 in 1977; the first genome sequence of a prokaryote (Haemophilus influenzae) was published in 1995; the yeast (Saccharomyces cerevisiae) genome was the first eukaryotic genome to be sequenced in 1996. The Human Genome Project was started in October 1990, and the first draft sequences of the human genome were reported in February 2001.

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Mitochondrial DNA in the context of Denisovan

The Denisovans or Denisova hominins (/dəˈnsəvə/ də-NEE-sə-və) are an extinct species or subspecies of archaic human that ranged across Asia during the Middle to Late Pleistocene, approximately 200,000–32,000 years ago. Most of what is known about Denisovans comes from DNA evidence. While many recent fossils have been found and tentatively identified as Denisovan, the first Denisovans discovered were known from few physical remains. Consequently, no formal species name has been established. However, an analysis of the mitochondrial DNA and endogenous proteins from the Harbin cranium, which had been given the name Homo longi, showed with great certainty that this species represents a Denisovan.In a study published in September 2025, remains from six additional sites in China including the 1 million year old Yunxian man were proposed to be included in the species Homo longi along with the genetically confirmed Denisovans.

The first identification of a Denisovan individual occurred in 2010, based on mitochondrial DNA (mtDNA) extracted from a juvenile finger bone excavated from the Siberian Denisova Cave in the Altai Mountains in 2008. Nuclear DNA indicates close affinities with Neanderthals. The cave was also periodically inhabited by Neanderthals. Additional specimens from Denisova Cave were subsequently identified, as were specimens from the Baishiya Karst Cave on the Tibetan Plateau, Tam Ngu Hao 2 Cave in the Annamite Mountains of Laos, the Penghu channel between Taiwan and the mainland, and Harbin in Manchuria.

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Mitochondrial DNA in the context of Takin

The takin (Budorcas taxicolor); /ˈtɑːkɪn/ is a large species of ungulate of the subfamily Caprinae found in the eastern Himalayas. It includes four subspecies, the Mishmi takin (B. t. taxicolor), the golden takin (B. t. bedfordi), the Tibetan (or Sichuan) takin (B. t. tibetana), and the Bhutan takin (B. t. whitei).

Whilst the takin has in the past been placed together with the muskox in the tribe Ovibovini, more recent mitochondrial research shows a closer relationship to Ovis (sheep). Its physical similarity to the muskox is therefore an example of convergent evolution. The takin is the national animal of Bhutan.

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Mitochondrial DNA in the context of Neanderthal genetics

Neanderthal genetics testing became possible in the 1990s with advances in ancient DNA analysis. In 2008, the Neanderthal genome project published the full sequence Neanderthal mitochondrial DNA (mtDNA), and in 2010 the full Neanderthal genome. Genetic data is useful in testing hypotheses about Neanderthal evolution and their divergence from early modern humans, as well as understanding Neanderthal demography, and interbreeding between archaic and modern humans.

Modern humans and Neanderthals had multiple different interbreeding episodes, but Neanderthal-derived genes in the present-day human genome descends from an episode 250,000 years ago probably in Eurasia, and 47,000 to 65,000 years ago in the Near East. While 20% of the Neanderthal genome survives today, most people only carry about a few percentage points of Neanderthal DNA, and most Neanderthal-derived DNA is non-coding. Neanderthals maintained a low genetic diversity and suffered from inbreeding depression; consequently most Neanderthal genes were probably selected out of the gene pool. Barring hybrid incompatibility or negative selection, most Neanderthal DNA may descend from the children of modern human females and Neanderthal males. Neanderthals also interbred with Denisovans in the Siberian Altai Mountains.

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Mitochondrial DNA in the context of Sperm

Sperm (pl.: sperm or sperms) is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Sperm cells contribute approximately half of the nuclear genetic information to the diploid offspring (excluding, in most cases, mitochondrial DNA). Animals produce motile sperm with a tail known as a flagellum, which are known as spermatozoa, while some red algae and fungi produce non-motile sperm cells, known as spermatia. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm.

Sperm cells form during the process known as spermatogenesis, which in amniotes (reptiles and mammals) takes place in the seminiferous tubules of the testicles. This process involves the production of several successive sperm cell precursors, starting with spermatogonia, which differentiate into spermatocytes. The spermatocytes then undergo meiosis, reducing their chromosome number by half, which produces spermatids. The spermatids then mature and, in animals, construct a tail, or flagellum, which gives rise to the mature, motile sperm cell. This whole process occurs constantly and takes around 3 months from start to finish.

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Mitochondrial DNA in the context of Lacewing

The Hemerobiiformia are a suborder of insects in the order Neuroptera that include most of the lacewings, antlions and their allies. The phylogeny of the Neuroptera was explored in 2014 using mitochondrial DNA sequences. The results indicate that the traditional Hemerobiiformia are paraphyletic, meaning that not all the members of the clade are considered to belong to it, in particular since it would include all the Myrmeleontiformia, with which the Hemerobiiformia were traditionally contrasted. The Osmyloidea, usually included in Hemerobiiformia, actually seem to represent a more ancient lineage basal to Hemerobiiformia as well as Myrmeleontiformia. The broken-up group is shown in the cladogram:

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