Recovering DNA
- Created by: AAntonianannetti
- Created on: 08-05-19 10:12
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- Recovering DNA
- Identification of biological evidence
- Locating biological material is necessary before appropriate collection
- Presumptive Tests - test which can establish the possibility that a specific bodily tissue/fluid is present
- Confirmatory Tests - tests which can identify a specific biological material
- Appropriate collection
- Prevent contamination
- PPE
- Prevent contamination
- Appropriate Packaging
- Prevent contaminaion
- Swabs, brown paper bags, tubes, wet/dry, frozen/ambient
- Prevent contaminaion
- Locating biological material is necessary before appropriate collection
- Types of biological material from a crime scene
- Semen
- A thick fluid containing sperm and other secretions from the male reproductive system
- The positive identification of semen can be extremely important in sexual abuse cases
- Presumptive Tests
- Alternative Light Source (ALS), Seminal Acid Phosphate Test (SAP)
- Confirmatory Tests
- Visualisation of sperm following staining, Lateral flow strips, mRNA analysis and PSA
- Blood
- Composed of red and white cells suspended in a liquid matrix called plasma.
- Generally visible to the naked eye but may not be clear against dark surface and if cleaning has been attempted.
- Salvia
- The fluid released when the mouth waters that plays an important role in both mechanical and chemical digestion
- Presumptive Tests
- Alternative Light Source and the Starch Iodine Test
- Confirmatory Test
- Lateral Flow Strips and mRNA analysis
- Semen
- Degradation of DNA Samples
- Forensic samples usually show degradation
- More cellular material is required to produce a DNA profile
- Sometimes it is not possible to produce a DNA profile
- More cellular material is required to produce a DNA profile
- In practice 15 or more cells are required to generate consistently good-quality DNA profiles from fresh material
- Forensic samples usually show degradation
- Identification of biological evidence
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