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

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

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

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.

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

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

17. Multilocus analysis - 7 loci

23. DNA Allele Interpretation

24. Grim Sleeper

25. Monozygotic (Identical) and Dizygotic (Fraternal) twins STR AnalysisMZ DZ DZ

26. Mitochondrial DNA

30. Y Chromosomal Inheritance

35. Homework
See Blackboard for Assignments for this Special Topic