Mitochondrial DNA profiling

• define mtDNA

  • mitochondrial DNA
  • materally inherited
  • clonal
  • works for degraded and old sample
  • hair, teeth and bone
  • high copy number
• what are mini-STRS


  small segments of conversional STRs
• features of mtDNA

  • fewer repair mechanisms
  • high mutation rate = high variability from maternal linage which is hinderance to establish famail realtionship
  • lack proof-reading
• explain location and structure of mtDNA

  • found in: mitochondria: membrane bound organelle in cyto of euk
  • circular: less suspectibale to exonuclease which breaks DNA
  • high copy number, increase chance to survive
• how many be and genes in a cell

  by: 16,569, but this can vary due to insertion/deletion

  gene: 37
• define non-coding region 


  1,122bp origins of rep for 1 of mtDNA does not code for any gene products
• D-loop

  • control region ”non-coding”
  • replication of mtDNA is here
  • has hyper variable regions (3)
• Coding region

  • uneven distribution of nucleotide = H and L strands
  • H strand: high number of G, codes for 28 genes
  • L strand: 9 genes
• explain mtDNA theory

  • egg gives all mtDNA to zygote
  • sperm sheds mtDNA before entry to egg
  • dilution by overwhelming number of mitochondria in egg
• heteroplasmy

  1. presence of 1+ mtDNA in indiv
  2. 2 types
  3. inherited: maternal/paternal and maternal germline
  4. accuquired: sub must “pt hetro” and deletion must “ length hetro”
• list ways heteroplasmy can be viewed

  1. 1+ mtDNA type in single tissue
  2. 1+ mtDNA type in tissue and homoplasmic in other
  3. heteroplasmic in 1 and homo in the other
• how to indicate heteroplasmy

  • indicated by Y
• uses of mtDNA

  • forensic
  • phylogeny
  • pop genetics
  • species ID
  • geneology
  • evolution
  • ancient DNA
• mtDNA markers

  1. SSR: simple seq repeats
  2. bi-allelic: SNPs and indels
• haplogroups

  • pop specific mtDNA
  • define different pop groups
  • defined by resistriction site - variation = SNPs
  • found throughout mtDNA genome
  • average number of base 9.5 -> 6
  • high mut rate = wide range of pop-specific base subs