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Forensic mitochondrial DNA sequencing. Female victim, found on road, had been run over by an SUV Investigation of area body shops showed an SUV that had been recently repaired for dented fenders The SUV had been washed and cleaned
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Forensic mitochondrial DNA sequencing • Female victim, found on road, had been run over by an SUV • Investigation of area body shops showed an SUV that had been recently repaired for dented fenders • The SUV had been washed and cleaned • However, a single hair, with no root, was recovered from a wheel
At the FBI crime lab: can DNA analysis match the hair to the victim? • What kind of DNA would be present in a hair shaft? • How can the analyst get enough DNA to analyze?
Mitochondrial DNA The greatest variation in DNA sequence is in the HV1 and HV2 regions
The polymerase chain reaction (PCR) is used to amplify mitochondrial DNA sequences Animation of PCR: How is PCR similar to, and different from, DNA replication in cells?
Which enzymes are required for both cellular DNA replication and PCR? • Helicase • DNA polymerase • DNA ligase • Primase • All of the above
What molecules are needed for both cellular DNA replication and PCR? • Primers • Deoxynucleotide triphosphates • Template DNA • All of the above • None of the above
Which primers will amplify the DNA sequence shown below? 5'-AGGCTGCGAT...//...CCGTTAGATT-3' 3'-TCCGACGCTA...//...GGCAATCTAA-5' 5'-AGGCTGCGAT-3' and 5'-CCGTTAGATT-3' 5'-AGGCTGCGAT-3' and 5'-AATCTAACGG-3' 5'-TCCGACGCTA-3' and 5'-GGCAATCTAA-3' 5'-TCCGACGCTA-3' and 5'-CCGTTAGATT-3' 3'-TCCGACGCTA-5' and 5'-CCGTTAGATT-3'
The PCR product is sequenced using Sanger dideoxy chain-termination Dye-terminator DNA sequencing animation www.dnalc.org/resources/animations/cycseq.html
The PCR product is sequenced using Sanger dideoxy chain-termination Dye-terminator DNA sequencing animation www.dnalc.org/resources/animations/cycseq.html
Q: If the Sanger sequence readout is 5’-GCAATCGA-3’, then what is the sequence of the template DNA? 5’-GCAATCGA-3’ 5’-AGCTAACG-3’ 5’-TCGATTGC-3’ 5’-CGTTAGCT-3’
Mitochondrial DNA from hairs from the victim and the SUV are compared Evidence hair From SUV Victim's hair Are these DNA sequences are identical? a) yes b) no
Can the two sequences be from the same person (heteroplasmy)? How could the FBI test this hypothesis?