Biology Case Work Introduction Flashcards
What are the pre- and post- PCR activities?
What is the presumptive test for differential extraction and the presence of semen?
The acid phosphatase test
* Visual examination/ light sources to localise the suspect stains
* Brentamine test: localise seminal acid phosphatase positive areas
* Will be a colour change in the presence of semen
* can decide to do either DNA extraction or differential DNA extraction
* Then a confirmatory test under the microscope
What should be seen under the microscopic examination for the presence of semen?
Sperm and epithelial cells
* Tails of sperm gives indication of how recent. Need to make notes of whether have tails or no tails
What components are needed for the differential extraction reaction for epithelial cells and sperm cells?
* Epithelial cells –> proteinase enzymes
* Sperm cells –> proteinase enzymes and DDT (dithiothreitol)
Why is DDT needed for sperm cells?
- acrosome in sperm have cysteine bound together (via disulphide bond) which is why we add DDT to break bond and release the nuclear material into solution
- Acrosome is heavy which is why the sperm goes to the bottom
What is the method for differential extraction?
EF= epithelial fraction
SF= Sperm fraction
Legal definition for common assault
Legal definitions for Actual bodily harm (ABH)
Legal definitions for grievous bodily harm (GBH)
What are the different types of sexual offence?
- Sexual assault
- Assault by penetration
- Rape
Definition of sexual assault
Definition of assault by penetration
Definition of Rape
What are sexual assault referral centres (SARCs) known as, and what are the three in London?
What happens to the sample taken if
(1) the victim directly came
(2) The victim came with the police
What are** early evidence kits (EEK)?**
Early evidence kits
If you report it to the police, they might offer you an early evidence kit to collect forensic evidence before you go for a forensic medical examination (if you decide to have one).
This lets us gather evidence that might otherwise be lost, like a urine sample if you need to go to the toilet, or a mouth swab if you want to eat or drink.
Whats the DNA recovery time in the following instances?
* DNA from fingers or DNA on penis (after vaginal penetration)
* DNA from skin to skin contact, fingernail scrapings or oral
* Lubricant from condom
* Anal
* Vaginal
Tell me the first convictions of DNA testing and how the testing was done
DNA fingerprint testing ( restriction enzymes –> agarose gel electrophoresis –> southern blotting –> radioactive probing –> x-ray film to visualise bands)
