Future of Forensics
What is a Mitochondrion?
Mitochondria are the most important part of a cell; this is where energy from food is converted into ATP. Although the nucleus contains the majority of our DNA, mitochondria have a small amount of their own DNA, known as mitochondrial DNA or mtDNA. mtDNA has only 16569 nucleotides compared to the 3 billion nucleotides of nuclear DNA; less than 1% of DNA is composed of mtDNA. While other types of DNA are long and linear, mtDNA is a small round circle. (Source: Mitochondrial DNA, mtDNA and Its Role in Ancestry, and DNA)
Mitochondrial DNA (mtDNA)
Mitochondrial DNA has a total 37 genes, which all control the function of the mitochondrion. Thirteen of these genes are responsible for oxidative phosphorylation, which produces ATP. Twenty-two genes provides the genetic code for making transfer RNA (tRNA) and 2 genes provides the instructions for making ribosomal RNA (rRNA). Both tRNA and rRNA produce amino acids that form proteins. (Source: What is Mitochondrial DNA?, Why is Mitochondrial DNA Important?, and mtDNA and Its Role in Ancestry)
When we were born, we receive DNA from both our mother and father, but mtDNA has an unique inheritance pattern. mtDNA is passed from only a mother to her child(ren) because the egg destroys the sperm's mitochondria during reproduction. Males carry their mother's mtDNA, but they do not pass it onto their child(ren). (Source: mtDNA and Its Role in Ancestry, All About DNA and Genetic Inheritance, and Other Genetic Principles)
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mtDNA Loop
The mtDNA loop is mainly composed of four regions: D-Loop (hypervariable region), rRNA, tRNA, and genes that provide genetic codes for proteins. The three regions that code for rRNA, tRNA, and proteins are also called the coding region. Every nucleotide in the mtDNA can be located by an accession number. The accession number starts at the origin, which is the D-Loop. From the D-Loop, it starts counting from 1 to 16569 clockwise. (Source: mtDNA and Its Role in Ancestry)
D-Loop
Although the D-Loop is the non-coding region of mtDNA, it contains the most information about ancestry. Since this region do not code genes, mutations occur within this region do not affect the person. Within the D-Loop, there are two regions: HVR 1 (locations 16000 through 16569) and HVR 2 (locations 1 through 400). (Source: mtDNA and Its Role in Ancestry)
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