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DNA Forensics. DNA Fingerprinting - What is It? Use of molecular genetic methods that determine the exact genotype of a DNA sample in a such a way that.

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Presentation on theme: "DNA Forensics. DNA Fingerprinting - What is It? Use of molecular genetic methods that determine the exact genotype of a DNA sample in a such a way that."— Presentation transcript:

1 DNA Forensics

2 DNA Fingerprinting - What is It? Use of molecular genetic methods that determine the exact genotype of a DNA sample in a such a way that the results distinguish one biological organism from another This unique genotype = DNA Profile

3 It’s not that complicated A DNA fingerprint is a method of looking at the similarities and differences that exist in organisms’ DNA sequences Distinguish one biological organism from another Individually discriminating southern blot minisatellite hybridization profile

4 Collect Tissue Sample How to do DNA Fingerprinting The Big Picture >1000 cells RFLP / Southern blot PCR Analysis >20 cells

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6 DNA Fingerprinting RFLP Determination of an individual’s unique collection of DNA restriction fragments

7 Collect Tissue Sample How to do DNA Fingerprinting The Big Picture >1000 cells RFLP / Southern blot >20 cells

8 Non Coding vs Coding DNA The majority of our genome is made up non coding DNA How much? Of this a large portion is of short sequences that are repeated, sometimes hundreds of times. There are numerous forms of this "repetitive DNA"

9 Short Tandem Repeats (STR’s) STR – region of DNA containing tandem copies of di-, tri- or tetranucleotide repeat units. Examples: Dinucleotide repeats: GTGTGTGTGTGT…… Trinucleotide repeats:ACGACGACGACG…… Tetranucleotide repeats:TATCTATCTATC……

10 More on STRs Number of repeats varies greatly between individuals STRs make up 10-15% of the mammalian genome STRs are also called “microsatellites”

11 Possible Patterns for a Single “Gene” With Three Alleles In a standard DNA fingerprint, about a dozen sites are analyzed, with each site having many possible alleles.

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13 PCR = Polymerase Chain Reaction

14 What is It? Basically DNA replication in a tube Needs the same basic components as DNA replication: DNA nucleotides, the building blocks for the new DNA Template DNA, the DNA sequence that you want to amplify Primers, single-stranded DNAs between 20 and 50 nucleotides long that are complementary to a short region on either side of the template DNA Taq polymerase, a heat stable enzyme that drives, or catalyzes, the synthesis of new DNA Targets a particular sequence and amplifies it many many, many, many times

15 PCR https://www.youtube.com/watch?v=2KoLnIwoZKU https://www.youtube.com/watch?v=2KoLnIwoZKU

16 CODIS Loci Combined DNA Index System 13 Loci across human genome

17 Multilocus analysis - 7 loci

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23 DNA Allele Interpretation http://www.newscientist.com/article/mg20727733.500- fallible-dna-evidence-can-mean-prison-or- freedom.html#.U0f7lsYh5W4 http://www.newscientist.com/article/mg20727733.500- fallible-dna-evidence-can-mean-prison-or- freedom.html#.U0f7lsYh5W4

24 Grim Sleeper

25 MZDZ Monozygotic (Identical) and Dizygotic (Fraternal) twins STR Analysis

26 Mitochondrial DNA

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30 Y Chromosomal Inheritance

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34 https://genographic.nationalgeographic.com

35 Homework See Blackboard for Assignments for this Special Topic


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