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Published byBrittney Holt Modified over 9 years ago
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DNA Forensics
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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
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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
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Collect Tissue Sample How to do DNA Fingerprinting The Big Picture >1000 cells RFLP / Southern blot PCR Analysis >20 cells
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DNA Fingerprinting RFLP Determination of an individual’s unique collection of DNA restriction fragments
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Collect Tissue Sample How to do DNA Fingerprinting The Big Picture >1000 cells RFLP / Southern blot >20 cells
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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"
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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……
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More on STRs Number of repeats varies greatly between individuals STRs make up 10-15% of the mammalian genome STRs are also called “microsatellites”
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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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PCR = Polymerase Chain Reaction
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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
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PCR https://www.youtube.com/watch?v=2KoLnIwoZKU https://www.youtube.com/watch?v=2KoLnIwoZKU
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CODIS Loci Combined DNA Index System 13 Loci across human genome
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Multilocus analysis - 7 loci
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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
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Grim Sleeper
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MZDZ Monozygotic (Identical) and Dizygotic (Fraternal) twins STR Analysis
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Mitochondrial DNA
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Y Chromosomal Inheritance
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https://genographic.nationalgeographic.com
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Homework See Blackboard for Assignments for this Special Topic
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