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Mitochondrial DNA is the small circular chromosome found inside mitochondria. These organelles, found in all eukaryotic cells, are the powerhouse of the cell. [1] The mitochondria, and thus mitochondrial DNA, are passed exclusively from mother to offspring through the egg cell.
Haplogroup R is a widely distributed human mitochondrial DNA (mtDNA) haplogroup. Haplogroup R is associated with the peopling of Eurasia after about 70,000 years ago, and is distributed in modern populations throughout the world outside of sub-Saharan Africa. [4] Haplogroup R is a descendant of the macro-haplogroup N.
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 ]
The variation of mitochondrial DNA between different people can be used to estimate the time back to a common ancestor, such as Mitochondrial Eve. This works because, along any particular line of descent, mitochondrial DNA accumulates mutations at the rate of approximately one every 3,500 years per nucleotide.
Haplogroup H is a human mitochondrial DNA (mtDNA) haplogroup. The clade is believed to have originated in Southwest Asia, near present day Syria, [1] around 20,000 to 25,000 years ago. Mitochondrial haplogroup H is today predominantly found in Europe, and is believed to have evolved before the Last Glacial Maximum (LGM).
English: Map of the human mitochondrial DNA genome (16569 bp, NCBI sequence accession NC_012920 — Anderson et al. 1981). The H (heavy, outer circle) and L (light, inner circle) strands are given with their corresponding genes.
In general, mitochondrial DNA lacks introns, as is the case in the human mitochondrial genome; [144] however, introns have been observed in some eukaryotic mitochondrial DNA, [146] such as that of yeast [147] and protists, [148] including Dictyostelium discoideum. [149] Between protein-coding regions, tRNAs are present.
The mitochondrial DNA variation in isolated "relict" populations in southeast Asia supports the view that there was only a single dispersal from Africa. [15] The distribution of the earliest branches within haplogroups M, N, and R across Eurasia and Oceania provides additional evidence for a three-founder-mtDNA scenario and a single migration ...