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In humans, mitochondrial DNA (mtDNA) forms closed circular molecules that contain 16,569 [4] [5] DNA base pairs, [6] with each such molecule normally containing a full set of the mitochondrial genes. Each human mitochondrion contains, on average, approximately 5 such mtDNA molecules, with the quantity ranging between 1 and 15. [6]
NUMT insertion into the nuclear genome and its persistence in the nuclear genome is initiated by the physical delivery of mitochondrial DNA to the nucleus. [5] This step follows by the mtDNA integration into the genome through a non-homologous end joining mechanism during the double-strand break (DSB) repair process as envisioned by studying Saccharomyces cerevisiae, [13] [29] and terminates ...
Nuclear DNA and mitochondrial DNA differ in many ways, starting with location and structure. Nuclear DNA is located within the nucleus of eukaryote cells and usually has two copies per cell while mitochondrial DNA is located in the mitochondria and contains 100–1,000 copies per cell.
Mitochondrial DNA is replicated by the DNA polymerase gamma complex which is composed of a 140 kDa catalytic DNA polymerase encoded by the POLG gene and two 55 kDa accessory subunits encoded by the POLG2 gene. [31] The replisome machinery is formed by DNA polymerase, TWINKLE and mitochondrial SSB proteins.
DNA polymerase's ability to slide along the DNA template allows increased processivity. There is a dramatic increase in processivity at the replication fork. This increase is facilitated by the DNA polymerase's association with proteins known as the sliding DNA clamp. The clamps are multiple protein subunits associated in the shape of a ring.
STR analysis is a tool in forensic analysis that evaluates specific STR regions found on nuclear DNA. The variable (polymorphic) nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA profile and another. [3] Scientific tools such as FBI approved STRmix incorporate this research technique.
Due to the proximity of the electron transport chain within the mitochondrial inner membrane and the production of reactive oxygen species (ROS), and due to the fact that the mtDNA molecule is not bound by or protected by histones, the mtDNA is more susceptible to DNA damage than nuclear DNA. [24] In cases where mtDNA damage does occur, the DNA ...
With the nuclear genome's 3.3 billion DNA base pairs in humans, one good example of a nuclear gene is MDH1 or the malate dehydrogenase 1 gene. In various metabolic pathways, including the citric acid cycle, MDH1 is a protein-coding gene that encodes an enzyme that catalyzes the NAD/ NADH -dependent, reversible oxidation of malate to oxaloacetate.