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DNA analysis

DNA analysis. DNA typing (genotyping) – History A marker is any polymorphic Mendelian character that can be used to follow a chromosomal segment through a pedigree. Phenotypical markers: E.g. blood groups Restriction Fragment Length Polymorphism

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DNA analysis

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  1. DNA analysis • DNA typing (genotyping) – History • A marker is any polymorphic Mendelian character that can be used to follow a chromosomal segment through a pedigree. • Phenotypical markers: E.g. blood groups • Restriction Fragment Length Polymorphism (RFLP) markers – The discovery of restriction enzymes not only provided a way to engineer the DNA, but for the first time, provided a marker that encompassed entire chromosome.

  2. Forensics – DNA analysis • RFLP • History • Southern analysis • Fragment length analysis • Frequency • Pattern used to identify individuals

  3. Minisatellite Variable Repeat Polymorphism (Analysis) First locus identified: D1S8 1990, Alec Jeffrey 19 bp for each repeat containing highly variable 1 bp in the HaeIII site Hundreds markers give sifficient polymorphism

  4. Forensics – DNA analysis • Polymerase Chain Reaction (PCR) • Discovery • Principles • Application examples • The case of the Russian Czar • The case of English Royals • Crime scene identification

  5. Short Tandem Repeats

  6. Forensics – DNA analysis Forensics – DNA analysis • Single Nucleotide Polymorphism - SNP • Sequence Polymorphism – DQa1

  7. Sequence Polymorphism

  8. RFLP DQa1 STR (VNTR) SNP Restriction enzymes Blot PCR DNA micro array Consideration of Markers • Length • Hybridization • Length • Hybridization Better Polymorphism Increased Density Less Sample Amounts Easier Test More Expensive

  9. Finding Common Characteristics of elements---Can you find common characters in the following figures? 1. These are “jollos”. 2. These are “plotz”. 3. Which are jollos and which are plotz? D E C A B

  10. “The bungled burglary” or “The burglar that couldn’t”

  11. The “missing person” case: Using PCR based polymarker loci GYPA, HBGG, D7S8, GC DQA1, STR TRIPLET. Gender identification locus: amelogenin Suspect & roommate excluded from blood on carpet and shoes. Roommate excluded. Suspect pled to first degree murder.

  12. The gender ID marker

  13. The case of disappearing sperm: DQa was the only locus validated for PCR testing in forensics at the time. No conclusion can be drawn from the test results

  14. The OJ Simpson case

  15. This was a few years ago. Now SNP typing marker concentration = one million / genome

  16. RFLP results 5 and 6; 7 and 9 are indistinguishable

  17. 3 5 13 Lane 3: Victim control Lane 5: Vaginal swab Lane 13: Andrew The first RFLP case (State v. Tommy Lee Andrews)

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