Mitochondrial DNA

Mitochondrial DNA

It can be used in forensics but is not used much. It cannot be used to reach the individual.

Forensic population DB has been analyzed in terms of haplogroup info to aid in quality control of the sample contained within a population group.

It can be used to see the tribe or race, evolutionary studies, migration all these can be determined through mitochondrial DNA.

Through databases, mitochondrial DNA can be compared to see race. The genome of mitochondria has a high mutation rate. But the data from various races can be collected and classified as Haplotypes. Denoted is 'i','j', etc. These are used to resolve ancestry issues.

There are multiple copies of mitochondrial DNA. It also depends on the type of cells the cells in which metabolic activity is more and have energy production then there will be more mitochondrial DNA in those.

There are certain regions in mitochondrial DNA which if amplified and sequenced then analysis can be carried like D Loop and Hypervariable (HV1 & HV2) to amplify specific regions choose that whose flanking regions are stable. The rate of mutation is not the same in the whole region of mitochondrial DNA some regions converse the regions against which primers are to be designed.

Mitochondria DNA is a small molecule. 16KB (16,569 bp). There are two strands in it.
Long Strand and Short Strand. (8-9 nucleotide deletion). There are 37 genes in it. The presence of 16s RNA indicates the symbiotic bacterial/ microbial origin of mitochondria.

Mitochondria from different cells will be different. All nucleotides do not match with one individual.

Mitochondrial DNA Polymerase does not have proofreading ability hence there are 10 times more mutations in it.

Characteristics Nuclear DNA Mitochondrial DNA
1 ● Size ● 3.2 billion bp ● 16.569 bp
2 ● Copies per cell ● Two copies ● > 1000 copies
3 ● % of total DNA ● 99.75% ● 0.25%
4 ● Structure ● Linear ● Circular
5 ● Inherited from ● Both parents ● Mother
6 ● Chromosomal pairing ● Diploid ● Haploid
7 ● Recombination ● ✓ ● ✘
8 ● Repair ● ✓ ● Limited
9 ● Mutation rate ● Low ● High

Interesting Points:
The genetic codon table of mitochondrial DNA is different.

  • UGA is a termination code in actual but in mitochondrial DNA it codes Tryptophan (W).
  • AUA codes for Methionine.
  • AGA & AGG are coding for Arginine normally but in mitochondrial DNA they are stop codons.
  • Mitochondrial DNA does not have good DNA repair Machinery.
  • Being circular in shape it is safer from the action of nucleases.
(Linear shape is not safe)

Case Study:
The grave of ISAR Nicholas II after the Bolsheviks revolution was found through mitochondrial DNA. Similarly, a woman named Anastasia, claiming to be Tsars’daughter was proved wrong through mitochondrial DNA.

Case Study Y chromosomal analysis
  • US president Thomas Jefferson & Sally Hemings (1802).
  • Paternity claim from a slave. For 200 years it was only thought that Sally Itomings was Jefferson's. In 200s legal descendants of both were taken for Y chromosome analysis. 19 STR sites were taken which matched exactly thus confirming slave sex without marriage.

Editor's Recommendation:

Mitochondrial DNA Mitochondrial DNA Reviewed by Abdullah on June 21, 2020 Rating: 5

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