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Forensic Biology by Richard Li

Explore cutting-edge techniques for DNA detection including gel electrophoresis, hybridization assays, fluorescence labeling, and PCR-based assays. Discover methods using ethidium bromide, radioisotope probes, biotin-avidin system, and fluorophores. Learn about UV transilluminator, chemiluminescence reporting system, and optical filters for precise analysis.

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Forensic Biology by Richard Li

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  1. Chapter 16: Detection Methods Forensic Biologyby Richard Li

  2. Direct Detection of DNA in Gels • Agarose Gels • Ethidium Bromide • Amounts as little as 10 ng per band • Including in the gel OR staining after electrophoresis • UV transilluminator at approx. 300nm & orange filter • Denatured Polyacrylmide Gels • Silver Nitrate • 100x more sensitive, lower cost, safer Forensic Biology by Richard Li

  3. Hybridization-Based Assay • Radioisotope Labeled Probes • VNTR testing & DNA quantification • Nick translation- dNTPs • Dnase I • P- most common radioisotope • Enzyme Conjugated Probes with Chemiluminescence Reporting System • Alkaline Phosphatase • Lumigen PPD Forensic Biology by Richard Li

  4. Hybridization-Based Assay • Biotin • Vitamin H found in egg yolk • Enzyme Conjugated Avidin • Glycoprotein found in egg whites • Binds to Biotin • Streptavidin • Horseradish peroxidase- contains Heme Forensic Biology by Richard Li

  5. Hybridization-Based Assay • Reporter Enzyme Assay • TMB- chromogenic substrate • Luminol-chemiluminescent substrate Forensic Biology by Richard Li

  6. Detection Methods for PCR-Based Assays • Fluorescence Labeling • Dyes • 400-600 nm • Labeling Methods • Primer method for STR (one primer) • Fluorescently labeled ddNTPs • Fluorophore Detection • Laser utilized as excitation source • Optical filters used to detect emitted light • Detector Forensic Biology by Richard Li

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