DNA Fingerprinting

1. DNA Fingerprinting TAKE NOTES!!! Covers A lot in Chaper 8!

2. Summary • Definition • History • How it works • Different Methods of processing • What it’s used for • Draw Backs • Final summary of presentation

3. QUESTION WHAT THE IS FORENSIC SCIENCE? WHAT THE IS DNA FINGERPRINTING?

4. Definition • Forensic science: Intersection of Law and Science • 1800’s: Photography • 1900’s: Actual Fingertips • Dna fingerprinting: Analysis of an organism’s unique DNA composition as a characteristic marker.

5. Question? Where did DNA fingerprinting come from?

6. History • 1985: United Kingdom • Sir Alex Jefferies • Dr. peter Gill • Dr. Dave Werrett • Norborough Village Murder

7. History Cont. • 1987: Florida USA • Tommie Lee Andrews • First person convicted of Rape • Used a sample of Tommie’s blood and a sperm sample from the crime scene

8. Question How does it work?

9. DNA 101 • Chemical Structure of DNA is always the same. • IMPORTANT: THE ORDER OF THE BASE PAIRS IS DIFFERENT! • 3 Billion Nucleotides form our 23 chromosomes • IMPORTANT: EVERY CELL CONTAINS A COPY OF OUR DNA!

10. How Does it work? • VNTR: variable number tandem repeats • VNTR- recognition that variable numbers of repeated nucleotides can be found in dna and can be used for identification of individuals

11. How Does it Work Cont. • VNTR’s: You get some from both parents • IMPORTANT: NO PERSON HAS VNTR’S THAT ARE IDENTICAL TO THEIR FOLKS • VNTR’s provide a scientific marker for identity. KEY ELEMENT!

12. What now Mr. Wizard? • FIRST: GET DNA! • Blood • Skin • Sperm • Spit • SECOND: Methods • RFLP • Dot Blot Analysis

13. RFLP • RFLP: Restriction fragment length polymorphism • Basically: Extract it, Chop it, Sort it, Photograph it

14. DNA is treated with Restriction Endonuclease Targets and cuts the Helix wherever a specific sequence appears Endonuclease is found in Bacteria like E.Coli Electrophoresis Negatively Charged DNA travels through a Gel towards a positively charged electrode. Smaller Fragments move faster! Gel is treated to get two single strands RFLP Cont.

15. Southern Blot Technique Probe it! Membrane is incubated with a radioactive or fluorescent strand of DNA Locus: Target Area of DNA Single Locus Probe Multi Locus Probe Hybridization Binding of the DNA fragment with it’s Probe Important: Probe will only bind to complementary parts! Everything else washed off! RFLP Still

16. RFLP: End! • X-Ray • Target dna is radioactive, it emits particles to make an image! • Autoradiograph

17. Question What is needed to complete the dot blot analysis?

18. PCR • Polymerase Chain Reaction • Basically: Take a small sample of DNA and use a Thermal Cycler to multiply the sample. • Warning! • If you start with the wrong sample you are screwed!

19. Locate the portion of DNA needed to study Thermal Cycler Enzyme: TAQ Polymerase DNA Nucleotides Cycle of Heat and Cold Thermal Cycler causes the DNA to separate and Replicate. PCR Key Element of Dot Blot Analysis. PCR

20. Dot Blot Analysis • Because of PCR the samples are identical and Electrophoresis is not needed. • Each dot on the analysis strip has a different DNA probe • Probe is a enzyme complex that can turn a colorless substrate into a colored one • Probe is chemically reactive not RADIOACTIVE

21. Dot Blot Cont. • Because human antibody alleles are different, the probability of a match can be concluded. • Important! • The dot sheet has a control dot, if it does not change color there wasn’t enough DNA

22. Almost done!

23. Just a recap • Definition • History (Briefly) • VNTR’s • RFLP • PCR • Dot Blot Analysis

24. Question what do we use DNA fingerprinting for?

25. Murders • Colin pitchfork • First guy to get convicted • Sir Alex Jefferies • Norborough Village Murder

26. Rape • 1987: Tommie Lee Andrews • 1988: Victor Lopez • Faulty eye witness • Women thought the attacker was black • test by swapping vaginal cells and testing sperm samples

27. Parental issues • Mitochondrial DNA: inherited from the mother only (cytoplasma of the egg) • Remains the same Generation to Generation • Traced through maternal line

28. Non Human Issues • American and Asian Ginseng • American: Boosts energy • Asian: Calm nerves • Pennsylvania: Bear was illegally killed • Pregnant Sow • DNA from den and check station

29. Setting Convicts Free • Innocent Protection Act of 2001 • Convicts access to DNA testing • Prohibits states from destroying Biological evidence • Kirk Bloodsworth

30. Drawbacks • Collecting samples • High temperatures can degrade DNA • Bacteria • Moisture • Human Error • Sneezes, improper storage, failure to label samples • Chain of Custody • Collection of evidence must be systematically recorded and access to evidence must be controlled

31. Final summary • Methods, Definitions, History • What it’s used for • Draw backs • THANKS FOR YOUR PARTICIPATION!

32. REFERENCES • Lecture 7: A few famous cases involving DNA Evidence. March 2007 • http://nitro.biosci.arizona.edu/courses/EEB195-2007/Lecture07/Lecture07.html • Baden, Michael. DNA Profiling. • http://www.kathyreichs.com/dnaprofiling.htm

33. REFERENCES CONT. • CHAPTER 8 IN THE TEXT BOOK • http://www.flickr.com/photos/davipt/228669699/ • http://www.untangledlife.com/wibrary/wp-content/upload/sperm_untangled%20life.jpg • http://www.admit-one.net/webimages/mrwizard.jpg