Forensic DNA Fingerprinting Lab Lab Objectives Use restriction
Forensic DNA Fingerprinting Lab
Lab Objectives • Use restriction enzymes to detect differences in the base sequences of individuals • Use gel electrophoresis to analyze DNA samples from suspects and crime scene DNA
DNA Fingerprint
DNA Fingerprinting • Technology used to analyze evidence in law enforcement cases and other applications such as: – Paternity testing – Determine evolutionary relationships among organisms (similarities and differences) – Diagnose genetic disorders or gene testing – Determination of impurities in a sample
Crime Scene DNA Analysis
Paternity Testing
Evolutionary Relationships
Restriction Enzymes • Enzymes that cut DNA at specific restriction sites - also known as recognition sequences • Used as a molecular tool • Found naturally in bacteria - evolved for protection against viruses • Over 3000 identified, 600 used commercially
Restriction Enzymes in Nature
Restriction Enzyme Recognition Sites
Restriction Enzymes Cut DNA • Use gel electrophoresis to compare multiple samples of DNA • Similar DNA samples have similar restriction sites and will produce fragments of similar sizes
RFLPs (Restriction Fragment Length Polymorphism) • A variation in the length of restriction fragments produced by a given restriction enzyme in a sample of DNA
RFLPs
Restriction Enzymes • Also used as tools in genetic engineering, for example, cloning • Cut and put together foreign pieces of DNA
Procedure Overview • DNA from crime scene and DNA from 5 potential suspects • Part 1: Restriction Digest of DNA Samples • Part 2: Agarose Gel Electrophoresis of DNA Samples
Jimmy Sweet
Cookie The Suspects Candy Honey Brandee Carmela
Part I: Restriction Digest of DNA Samples • • Eco. RI/Pst. I enzyme mix (ENZ) Crime scene DNA (CS) - green Suspect 1 (S 1) - blue Suspect 2 (S 2) - orange Suspect 3 (S 3) - violet Suspect 4 (S 4) - pink Suspect 5 (S 5) – yellow Ice and a 37 °C water bath
Part II: Agarose Gel Electrophoresis • Add 5 u. L of loading dye (LD) into each sample • Load gel as follows: – Lane 1 – S, DNA size standard – 10 µL – Lane 2 – CS, green tube – 20 µL – Lane 3 – S 1, blue tube – 20 µL – Lane 4 – S 2, orange tube – 20 µL – Lane 5 – S 3, violet tube – 20 µL – Lane 6 – S 4, red tube – 20 µL – Lane 7 – S 5, yellow tube – 20 µL
- Slides: 19