Mitochondria DNA Functions and Forensics

From memory, I know mitochondria are very important for each and every cell, so that we may produce energy. This organelle is able to contribute to the breakdown of complicated molecules to produce ATP required for our bodies to function efficiently. It also has its own DNA which made some theorize that early cells were made by bacteria which integrated themselves into others eventually becoming what we know. This mitochondrial organelle can be transferred from mother to children since it is in the egg which is used during fertilization. This mitochondrial DNA has been used for tracing back origins of mankind and it is useful for forensic analysis in some cases. It also seems to be related that as we age the mitochondria develop mutations.

As we have mentioned there is mitochondrial DNA present in our cells which are inherited from our mother. These can be obtained in certain samples to get a hint of who was present at the crime scene. Our own nuclear DNA could also be used but this is limited to one copy per cell. Our mitochondrial DNA could be replicated several times over in one cell. This allows for mitochondrial DNA to have a higher possibility of being retrieved during investigations. I imagine when little living materials are left due to possibly a fire or other mass casualty this sequence can be used to identify a person. If possible material DNA can be retrieved for comparison.

Some issues with using mitochondrial DNA is that this information is usually like a mothers' mitochondrial DNA. This means brothers, sisters, children if you are female, and mothers would all have similar information. This could cause issues if all these parties may be involved.

We know that mitochondria mutations play roles in tumor growth and some neurogenerative diseases.  We are finding that there is some correlation with age. This can assist in identifying an unknown person by finding out a possible age of the victim. Different techniques can be used and known gene information may be able to assist. When viewing the 4977 bp in skeletal muscle we can have a rough estimate of age and differ between young and old. In another case, there is evidence that mutations at the A189G location had high levels in those who were 60 or older. I find it interesting that not only is DNA used to identify a person who may have the same sequence but it can be used to find more about their physical appearance at the time. It would be interesting to see a program which only needs a human genetic sequence to be entered which will estimate how a person would grow, age, and how their facial features would appear.

There is still information we are learning about when it comes to mitochondria. As I have mentioned we are seeing some relationship in age-related changes, which may be due to how the mitochondria make oxidative radicals, and we are finding how certain areas of the body have different results when mitochondria are obtained. Hair has been found to receive different results by hair fragment. The study search for a hotspot on the mitochondria for this property but a definite pattern was not found.

Going into this I thought the use of mitochondria DNA had the main use of being more available and more likely to be found due to the amount of it and the structure of mitochondria, but there is more to this other section of DNA than I once thought.

Sources:

mtDNA Mutations and Their Role in Aging, Diseases and Forensic Sciences
Zapico, Sara C. & Ubelaker, Douglas H.

Hairy matters: MtDNA quantity and sequence variation along and among human head hairs
Stijn Desmytera, Martin Bodner, Gabriela Huber, Sophie Dognaux, Cordula Berger, Fabrice Noël, Walther Parson

Forensic DNA: Mitochondrial DNA
https://www.nij.gov/topics/forensics/evidence/dna/research/pages/mitochondrial.aspx