Mitochondrial DNA

DNA is mainly packaged with a wide range of chromosomes in the nucleus. Mitochondria have DNA material popularly known as mtDNA or mitochondrial DNA.  Within the DNA are structures in the cells that convert energy from food into a more useful form that cells can utilize. Each cell contains up to thousands of mitochondria located in the fluid surrounding the cytoplasm.

Mitochondria cells produce energy through oxidative phosphorylation process and this process utilizes simple sugars and oxygen to create adenosine triphosphate, the main source of energy for the cells. A set of enzymes is however designated as complexes I to V and they carry out the oxidative phosphorylation process within the mitochondria.

Besides energy production, mitochondria play a crucial role in different cellular activities. For instance, mitochondria regulate apoptosis or self-destruction of cells. They are also essential in the production of heme, a hemoglobin component or a molecule that carries oxygen in the blood. It also produces cholesterol.

Mitochondrial DNA has 37 genes. All the genes play an important role in ensuring normal functioning of the mitochondria. Thirteen of the genes offer instructions to ensure enzymes participate in oxidative phosphorylation process. The remaining genes offer instructions for transfer of molecules called RNA’s OR r RNAs and RNA or t RNAs. These are chemical cousins to or of DNA and are important types of RNA because they assemble protein building blocks or amino acids into more functioning proteins.

Characteristics of Mitochondrial DNA

Mitochondrial DNA has some of the following characteristics

• It is circular in shape and is built with of 16, 569 base pairs
• It has 37 genes encoding 13 proteins 2 r RNAs and 22 tRNAs
• It has 13 mitochondrial gene encoded proteins that instruct cells to produce subunits of protein enzymes
• Small mitochondria genome cannot produce proteins independently and heavily depend on imported nuclear gene products
• Mitochondria have copies of its mitochondrial DNA. Each cell has numerous mitochondria and any given cell has thousands of cells

• It is not enveloped or packaged into chromatin
• It has noncoding DNA sequences and in some cases none
• Mitochondrial nucleotide bases its function on one gene
• In mitochondrial DNA, the mode of inheritance is basically maternal
• Genes on both DNAs are transcribed in a unique polycistronic manner
• Prospects and advances in Mitochondrial DNA

The role of mtDNA must be considered in regards to genetic human diseases.  The heterogeneity of the cells presents a wide range of challenges to researchers in relation to neurodegenerative diseases including diabetes, cancer and in aging.

MtDNA also plays a significant role in genetics for instance; it has been widely used to answer concerns about distribution of humans across the globe. Mitochondria are passed through maternal lineage and there is very little recombination in the DNA. In the case of paternal lineages it has been widely used to determine how humans migrated and occupied different parts of the globe.

Through  Human Mitochondrial DNA  studies, it has also been easy to establish how human populations in today’s age and era left Africa and other continents many years ago for instance, how some individuals left Africa 170, 000 years ago.

Summary

Mitochondrial genome or gene is small in size and even so, it plays a crucial role in ensuring that the powerhouse of body cells function cell. The circular genome is also plentiful compared to its nuclear counterpart and as a result, highly prone to mutation. Presently, it can be quite difficult to predict the manner in which mtDNA mutations pass from a mother to child because of the interplay between nuclear genomes and mitochondrial genomes.

In spite of the above, mtDNA mutations are not necessarily a bad thing. They are introduced in different ways into mtDNA sequences through mutations. Therefore, they play a crucial role in linking family members together and in reuniting missing children with their sisters, brothers, grandmothers and mothers. Much is however to be learnt about this kind of DNA and there are many ongoing studies for this fascinating DNA to help expand human understanding of human history and human diseases for many years to come.

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Sources

http://www.nature.com/scitable/topicpage/mtdna-and-mitochondrial-diseases-903

http://www.talkorigins.org/faqs/homs/mtDNA.html

The Fire Within: The Unfolding Story of Human Mitochondrial DNA,

 Human Mitochondrial DNA,