1. DNA Analysis

2. What is DNA? Deoxyribonucleic Acid Genes found on a chromosome are composed of DNA DNA contains all of our body’s genetic material

3. DNA Structure Composed of a sugar, phosphate group and a nitrogen base Sugar: Deoxyribose Phosphate group: Phosphate ion Nitrogenous bases: Adenine, Guanine, Cytosine, Thymine

5. Complimentary Base Pairing Adenine with Thymine Guanine with Cytosine

6. Major Sources of DNA Blood Saliva Hair with a root Semen Skin

7. Collecting DNA 1. Wear disposable gloves 2. Use disposable instruments for each sample 3. Avoid touching the area where DNA may be found 4. Avoid talking, sneezing and coughing over evidence (mask) 5. Avoid touching your face, nose and mouth when collecting evidence

8. Collecting DNA 6. Air-dry evidence thoroughly before packaging 7. Put evidence into new paper bags or envelopes 8. If wet evidence cannot be dried, it may be frozen

9. Mitochondrial DNA DNA found only in the mitochondria of the cell Inherited from the MOTHER ONLY

10. Mitochondria DNA Advantages ◦ More sensitive than nuclear DNA (less needed for testing) ◦ Degrades slower than nuclear DNA ◦ Can be used in cases where nuclear DNA cannot (hair w/o root, skeletal remains)

11. Mitochondrial DNA Disadvantages ◦ All people of the same maternal line will be indistinguishable ◦ More work, more time consuming, more costly

12. Junk DNA 95% of your genetic code doesn’t code for any protein This means that only 5% creates the proteins (genes) that make you, YOU!

13. Variable Number Tandem Repeats (VNTR’s) Short identical repeat sequences of DNA A particular sequence that you want to be copied can be repeated up to 30 times Used so you can test multiple times

14. Short Tandem Repeats (STR’s) Repeats of 2-7 bases with a total length of 100-400 base pairs They are shorter so they are less susceptible to breakage Loci of choice for laboratory analysis Ideal size for PCR (Polymerase Chain Reaction)

15. FBI Standard Reference Loci

16. DNA Fingerprinting Used to identify individuals by their STR regions

17. Steps to creating a DNA fingerprint 1. Isolate the DNA 2. Cut the DNA at a specific site using a restriction enzyme to create short DNA fragments 3. Use PCR to amplify the fragments 4. Sort the fragments according to size using gel electrophoresis

18. Steps Cont. 5. Use a radioactive probe to label the VNTR’s that you wish to look at 6. Use x-ray film to take a picture or view you gel over a light source

19. Restriction Fragment Length Polymorphism (RFLP’s) Occurs when the genetic length of a specific fragment varies between individuals

20. Polymerase Chain Reaction (PCR) Devised in 1983 to amplify small amounts of DNA Can be performed using the DNA from 1 cell The amplified DNA can then be used to: - Identify a suspect or victim, determine sex, determine species

21. PCR Technique

22. CODIS Combined DNA Index System National software developed by the FBI Distributed to local, state and national crime labs All 50 states mandate inclusion of DNA fingerprints from all violent criminals and sex offenders

23. CODIS Uses 13 STR regions Thousands of matches have led to the capture of criminals that otherwise would never have been caught It has also led to the exoneration of many criminals wrongfully imprisoned