MtDNA mitochondrial DNA

Mitochondria are unique organelles in man and higher animals in that they contain their own genome. Mitochondrial DNA (mtDNA) in humans is a small (16.5 kb), circular genome that encodes only 13 proteins, 22 transfer RNA (tRNA), and 2 ribosomal RNA (rRNA) molecules. mtDNA is inherited only from the mother and is present in multiple copies within one mitochondrion. 

The third human DNA SRM developed by NIST was designed to meet the need for quality control when amplifying and sequencing human mitochondrial DNA (mtDNA). 

While DNA is more robust than often depicted in movies, age and extreme conditions such as a fire can substantially degrade it. In such cases, mitochondrial DNA (mtDNA) is best used. Unlike nuclear DNA, mitochondrial genome exists in thousands of copies, is less apt to degrade, and is inherited only from the mother. Here, STRs are not analyzed, but rather the focus is on variable regions of the mitochondrial genome. Such analyses take much longer but are used for situations where time is not essential. 

Nucleoside analogues are drugs used to treat HIV and hepatitis. One such drug fialuridine and other drugs of this type have caused severe hepatic dysfunction. This dysfunction was characterized by fatty liver and fatal liver failure. Fialuridine caused fatal damage in 5 of 12 patients in early clinical trials. Fialuridine inhibits DNA polymerases. However, there is also DNA in the mitochondria [mitochondrial DNA (mtDNA)]. 

Eukaryotic cells also have organelles, mitochondria (Fig. 24-6) and chloroplasts, that contain DNA. Mitochondrial DNA (mtDNA) molecules are much smaller than the nuclear chromosomes. In animal cells, mtDNA contains fewer than 20,000 bp (16,569 bp in human mtDNA) and is a circular duplex. Each mitochondrion typically has two to ten copies of this mtDNA molecule, and the number can rise to hundreds in certain cells when an embryo is undergoing cell differentiation. In a few organisms (trypanosomes, for example) each mitochondrion contains thousands of copies of mtDNA, organized into a complex and interlinked matrix known as a kinetoplast. Plant cell mtDNA ranges in size from... 

Of the very few variations in the genetic code that we know of, most occur in mitochondrial DNA (mtDNA), which encodes only 10 to 20 proteins. Mitochondria have their own tRNAs, so their code variations do not affect the much larger cellular genome. 

H. citelli, H. diminuta and H. microstoma, one of which is mitochondrial DNA (mtDNA) (394). The mtDNA of H. diminuta has been isolated (118) and has been shown to be a typical circular molecule. The characteristics of H. diminuta DNA are shown in Table 6.11. In contrast, E. multilocularis and E. granulosus produced two distinct DNA bands after fractionation in caesium chloride, but there was no evidence that the DNA from either band represented mtDNA (493). There is presumably so little mtDNA in comparison to nuclear DNA in these organisms that it is completely masked in preparations of total DNA by this method. That this is the case has been shown by a recent study (976), where a different procedure, based on the selective precipitation of nucleic acids by cetyltrimethylammonium bromide (CTAB), was employed to extract mtDNA from isolated mitochondria. Some 300 g and 50 g, respectively, of Taenia spp. and Echinococcus sp. tissue yielded approximately only 1 ng mtDNA. 

Human mitochondrial DNA (mtDNA), a circular supercoiled DNA of about 16,469 base pairs, codes for 13 proteins, 22 tRNAs, and 2 ribosomal RNAs (rRNAs) using a code slightly different from the virtually universal code (page... 

Mitochondrial DNA (mtDNA), which is clonally inherited through maternal lineages, has proved to be a powerful genetic marker for phyloge-... 

Mitochondrial DNA (mtDNA) is present in mitochondria as a circular molecule and in most species codes for 13 or 14 proteins involved in the electron transfer chain, 2 rRNA subunits and 22 tRNA molecules (all necessary for protein synthesis) (Table 16.1). Given that 80% of mtDNA codes for functional mitochondrial proteins involved in energy production, it is not surprising that mtDNA mutations commonly lead to functional problems that manifest as muscle disorders (myopathies). 

All three respiratory complexes are typical integral membrane proteins that span the inner mitochondrial membrane. Each consists of several different subunits, the exact number of which is still under debate. The genes of some subunits of cytochrome oxidase and the />c, complex are in mitochondrial DNA (mtDNA). These proteins are synthesised inside the mitochondrion. However, most proteins of these complexes, as well as cytochrome c, are synthesised on cytoplasmic ribosomes and coded by the nuclear genome. This raises intriguing questions of how the latter are imported into the mitochondrion and inserted into the mitochondrial membrane, as well as of how mitochondrial and cytoplasmic transcription and translation are synchronised [3-5]. 

In parallel to that, two other techniques are being utilized with specific objectives. They include mitochondrial DNA and Y chromosome DNA analysis. Mitochondrial DNA (mtDNA) is a double-stranded DNA... 

Mitochondrial genomes are circular double-stranded DNA molecules, which are 16,569 base pairs long, that are present as one or more copies within the mitochondria of a cell. Thus mitochondrial DNA (mtDNA) is present in hundreds to thousands of copies per cell. MtDNA, unlike chromosomal DNA, does not undergo meiosis and does not participate in genetic recombmation events. MtDNA remains stable over generations, except for the acquisition of mutations at a rate 10 to 20 times that of nuclear DNA. 

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